Luminance uniformity compensation of vector projection display

ABSTRACT

A method to display a projected parametric curve upon a substantially transparent windscreen head-up display includes monitoring a desired parametric curve comprising a plurality of control points and a plurality of graphic segments based upon the control points, determining a luminance indicator for each of the segments, and utilizing the luminance indicator to command uniform luminance among the plurality of graphic segments.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.12/417,077 filed on Apr. 2, 2009 which is hereby incorporated herein byreference.

TECHNICAL FIELD

This disclosure is related to graphical imaging upon a windscreen in amotor vehicle.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Presentation of information to the operator of a vehicle in an effectivemanner is desirable and reduces strain upon the operator. Displaytechniques are known wherein light is projected upon a screen, and thelight is converted into a viewable display upon the screen. Applied totransportation applications, such displays are known as head-updisplays, wherein information is projected upon a visor, a screenbetween the operator and a windscreen, or directly upon the windscreen.However, known systems projecting light directly upon a windscreenfrequently require a coating or material that significantly decreasesthe transparency of the windscreen. As a result, head-up displays arefrequently restricted to limited region upon the windscreen.

Vehicle systems monitor a great deal of information. In particular,vehicle systems utilizing driving aids such as adaptive cruise control(ACC), automatic lateral control, collision avoidance or preparationsystems, and lane keeping aids monitor and process information regardingthe operating environment surrounding the vehicle. Additionally,information is available from a variety of sources to locate the vehiclein relation to a 3D map database, plan a travel route for the vehicle toa destination, and correlate this travel route to available informationregarding the route. Additionally, on-board vehicle systems provide awide variety of information that can be used to improve control of thevehicle. Additionally, vehicle to vehicle communications are known toutilize data collected in one vehicle in communicating with vehicleselsewhere on the road.

SUMMARY

A method to display a projected parametric curve upon a substantiallytransparent windscreen head-up display includes monitoring a desiredparametric curve including a plurality of control points and a pluralityof graphic segments based upon the control points, determining aluminance indicator for each of the segments, and utilizing theluminance indicator to command uniform luminance among the plurality ofgraphic segments.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 depicts an exemplary vehicle equipped with an EVS system, inaccordance with the present disclosure;

FIG. 2 is an example diagram of a substantially transparent display, inaccordance with the present disclosure;

FIG. 3 depicts an exemplary graphic projection upon a surface, inaccordance with the present disclosure;

FIG. 4 illustrates a scheme for utilizing excitation light to emitvisible light from the HUD, in accordance with the present disclosure;

FIG. 5 depicts an exemplary arrangement of light emitting particles upona substrate, in accordance with the present disclosure;

FIG. 6 illustrates different types of light emitting materials layeredon a substrate, in accordance with the present disclosure;

FIG. 7 is an exemplary diagram of the excitation and emissionrelationships of different light emitting materials, in accordance withthe present disclosure;

FIG. 8 is an exemplary diagram of a pattern of microstructures dispersedin a substantially transparent or translucent substrate, in accordancewith the present disclosure;

FIG. 9 is an example diagram of a pattern of microstructures disposed ona surface of a substantially transparent or translucent substrate,similar to FIG. 8, in accordance with the present disclosure;

FIG. 10 is an example diagram of an angled pattern of microstructuresdispersed in a substantially transparent or translucent substrate,similar to FIG. 8, in accordance with the present disclosure;

FIG. 11 illustrates an exemplary embodiment of a two-dimensional lightbeam based FC display subsystem, in accordance with the presentdisclosure;

FIG. 12 shows a schematic diagram of the vehicle 10 system which hasbeen constructed with a target tracking system, in accordance with thepresent disclosure;

FIG. 13 depicts an information flow utilized in creating a track list,in accordance with the present disclosure;

FIG. 14 depicts an exemplary data fusion process, in accordance with thepresent disclosure;

FIG. 15 depicts an exemplary dataflow enabling joint tracking and sensorregistration, in accordance with the present disclosure;

FIG. 16 schematically illustrates an exemplary system whereby sensorinputs are fused into object tracks useful in a collision preparationsystem, in accordance with the present disclosure;

FIG. 17 schematically illustrates an exemplary image fusion module, inaccordance with the present disclosure;

FIG. 18 schematically depicts an exemplary bank of Kalman filtersoperating to estimate position and velocity of a group objects, inaccordance with the present disclosure;

FIG. 19 illustrates exemplary range data overlaid onto a correspondingimage plane, useful in system-internal analyses of various targetobjects, in accordance with the present disclosure;

FIG. 20 depicts an exemplary vehicle utilizing a sensor to acquire roadgeometry data in front of a vehicle, in accordance with the presentdisclosure;

FIG. 21 illustrates an exemplary forward lane estimation process, inaccordance with the present disclosure;

FIG. 22 depicts an exemplary process wherein information from a mapdatabase can be utilized to construct a geometric model of a road in anarea of a vehicle, in accordance with the present disclosure;

FIG. 23 graphically illustrates an exemplary iterative method to find anapproximate location of a vehicle with respect to an estimated roadgeometry, in accordance with the present disclosure;

FIG. 24 depicts an exemplary vehicle pose localization process, inaccordance with the present disclosure;

FIG. 25 illustrates an exemplary determination made within the lateralmodel of the vehicle, in accordance with the present disclosure;

FIG. 26 illustrates an exemplary use of waypoints along a projected lanein front of the vehicle to estimate lane geometry, in accordance withthe present disclosure;

FIGS. 27-29 illustrate an exemplary application of contextualinformation to sensed object data in order to determine whether thesensed data is critical information, in accordance with the presentdisclosure;

FIG. 27 depicts a vehicle including three sequential data pointsdescribing a target object in front of the vehicle;

FIG. 28 depicts an exemplary situation in which corresponding datapoints would correctly indicate critical information to an operator; and

FIG. 29 depicts an exemplary situation in which corresponding datapoints could incorrectly indicate critical information to an operator;

FIGS. 30 and 31 schematically depict an exemplary use of a pixelatedfield of view limited architecture, in accordance with the presentdisclosure;

FIG. 30 depicts an exemplary emitter, capable of emitting light to alimited field of view; and

FIG. 31 describes an exemplary process to create the necessary structureof emitters aligned to a polymer substrate in order to enable limitedfield of view viewing;

FIGS. 32-37 illustrate select exemplary displays of critical informationthat might be projected upon a HUD, in accordance with the presentdisclosure;

FIG. 32 depicts an exemplary un-enhanced external view includingfeatures that are desirably visibly accessible to an operator of avehicle;

FIG. 33 depicts an exemplary view obstructed by heavy fog and exemplaryenhanced vision displays that may be used to compensate for the effectof the fog;

FIG. 34 depicts an exemplary display of graphics improving safetythrough a lane change;

FIG. 35 depicts an exemplary situation wherein a peripheral salientfeature enhancement feature is utilized in combination with an estimatedoperator's gaze location to alert an operator to critical information;

FIG. 36 depicts an exemplary view describing display of navigationaldirections upon a HUD;

FIG. 37 depicts an additional exemplary view, describing criticalinformation that can be displayed upon a HUD;

FIG. 38 schematically depicts an exemplary information flowaccomplishing methods described above, in accordance with the presentdisclosure;

FIG. 39 schematically depicts an exemplary luminance correction systemfor projecting a projected parametric curve upon a projection surface,in accordance with the present disclosure;

FIG. 40 illustrates a parametric curve including a plurality of controlpoints and segments associated therewith, in accordance with the presentdisclosure; and

FIG. 41 illustrates a re-parameterized parametric curve including aplurality of new equidistantly spaced control points and segmentsassociated therewith, in accordance with the present disclosure.

DETAILED DESCRIPTION

Referring now to the drawings, wherein the showings are for the purposeof illustrating certain exemplary embodiments only and not for thepurpose of limiting the same, a method utilizing an enhanced visionsystem (EVS) to represent graphical images upon a windscreen of avehicle describing an operational environment for the vehicle isdisclosed. The graphical images originate from sensor and/or data inputsdescribing the operational environment and include processing of theinputs in order to convey critical information to the operator oroccupants of the vehicle. Graphical images to be displayed upon thewindscreen are additionally registered to the visible relevant featuresobservable through the windscreen, such that an intended occupant mayview the relevant feature and the registered graphical image as a singlediscernable input.

FIG. 1 depicts an exemplary vehicle equipped with an EVS system, inaccordance with the present disclosure. Vehicle 100 includes an EVSsystem manager 110; vehicle sensor systems, including camera system 120and radar system 125; vehicle operation sensors, including vehicle speedsensor 130; information systems, including GPS device 140 and wirelesscommunication system 145; head-up display (HUD) 150; EVS graphics system155; graphics projection system 158; and occupant eye location sensingsystem 160. The EVS system manager 110 includes a programmable processorincluding programming to monitor various inputs and determine whatinformation is appropriate to display upon the HUD. The EVS systemmanager can communication directly with various systems and components,or the EVS system manager can alternatively or additionally communicateover a LAN/CAN system 115. The EVS system manager utilizes informationregarding the operational environment of the vehicle derived from anumber of inputs. Camera system 120 includes a camera or image capturingdevice taking periodic or sequential images representing a view from thevehicle. Radar system 125 includes a device known in the art utilizingelectromagnetic radiation to detect other vehicles or objects locatednear the vehicle. A number of known in-vehicle sensors are widely usedwithin a vehicle to monitor vehicle speed, engine speed, wheel slip, andother parameters descriptive of the operation of the vehicle. Exemplaryvehicle speed sensor 130 is depicted to represent such an in-vehiclesensor describing vehicle operation, but the disclosure intends toinclude any such sensors for use by the EVS. GPS device 140 and wirelesscommunication system 145 are devices known in the art for communicatingwith resources outside of the vehicle, for example, satellite system 180and cellular communications tower 190. GPS device 140 may be utilized inconjunction with a 3D map database including detailed informationrelating to a global coordinate received by the GPS device 140 regardingthe current location of the vehicle. HUD 150 includes a windscreenequipped with features capable of displaying an image projectedthereupon while remaining transparent or substantially transparent suchthat occupants of the vehicle can clearly observe outside of the vehiclethrough the windscreen. One will appreciate that while HUD 150 includesthe windscreen in the front of the vehicle, other surfaces within thevehicle could be used for projection, including side windows and a rearwindow. Additionally, the view on the front windscreen could becontinued upon the front vehicle “A-pillars” and onto the side windowsas a continuous image. EVS graphics engine 155 includes display softwareor programming translating requests to display information from the EVSsystem manager 110 in graphical representations describing theinformation. The EVS graphics engine 155 includes programming tocompensate for the curved and tilted surface of the windscreen and anyother surfaces onto which graphics are to be projected. EVS graphicsengine 155 controls graphics projection system 158 including a laser orprojector device producing an excitation light to project the graphicalrepresentations. Occupant eye location sensing system 160 includessensors known in the art to approximate a location of the head of anoccupant and further the orientation or gaze location of the eyes of theoccupant. Based upon the output of the occupant eye location sensingsystem 160 and input data tracking location information regarding theenvironment around the vehicle, EVS system manager 110 can accuratelyregister the graphical representations to the HUD such the occupant seesthe images overlaid with visual images through the windscreen.

The EVS described above includes eye sensing and head sensing devicesallowing estimation of eye location, allowing registration of imagesupon the HUD such that the images correspond to a view of the operator.However, it will be appreciated that estimation of head and eye locationcan be achieved through a number of methods. For example, in a processsimilar to adjusting rearview mirrors, an operator can use a calibrationroutine upon entering a vehicle to align graphics to a detected object.In another embodiment, seat position longitudinally in the vehicle canbe used to estimate a position of the driver's head. In anotherembodiment, manual adjustment of a rearview mirror or mirrors can beused to estimate location of an operator's eyes. It will be appreciatedthat a combination of methods, for example, seat position and mirroradjustment angle, can be utilized to estimate operator head locationwith improved accuracy. Many methods to accomplish accurate registrationof graphics upon the HUD are contemplated, and the disclosure is notintended to be limited to the particular embodiments described herein.

An exemplary EVS includes a wide field of view, full windscreen (HUD), asubstantially transparent screen including functionality to displaygraphical images projected thereupon; a HUD image engine including alaser or lasers capable of projecting images upon the windscreen; inputsources deriving data concerning the operating environment of thevehicle; and an EVS system manager including programming to monitorinputs from the input devices, process the inputs and determine criticalinformation relative to the operating environment, and create requestsfor graphical images to be created by the HUD image engine. However, itwill be appreciated that this exemplary EVS is only one of a wide numberof configurations that an EVS can take. For example, a vision or camerasystem is useful to various EVS applications that will be discussed.However, it will be appreciated that an exemplary EVS system can operatewithout a vision system, for example, providing information availablefrom only a GPS device, 3D map database, and in-vehicle sensors. In thealternative, it will be appreciated that an exemplary EVS system canoperate without access to a GPS device or wireless network, insteadutilizing inputs only from a vision system and radar system. Manyvarious configurations are possible with the disclosed systems andmethods, and the disclosure is not intended to limited to the exemplaryembodiments described herein.

The windscreen including HUD is important to operation of the EVS. Inorder to function as a medium through which relevant features areobservable while serving as a display device upon which the graphicalimages may be displayed, the windscreen of the vehicle must be bothtransparent and capable of displaying images projected by an excitationlight source. FIG. 2 is an example diagram of a substantiallytransparent display, in accordance with the present disclosure. Viewer10 is able to see an arbitrary object (e.g. cube 12) through substrate14. Substrate 14 may be transparent or substantially transparent. Whileviewer 10 sees arbitrary object 12 through substrate 14, the viewer canalso see images (e.g. circle 15 and triangle 16) that are created atsubstrate 14. Substrate 14 may be part of a vehicle windshield, abuilding window, a glass substrate, a plastic substrate, a polymersubstrate, or other transparent (or substantially transparent) mediumthat would be appreciated by one of ordinary skill in the art. Othersubstrates may complement substrate 14 to provide for tinting, substrateprotection, light filtering (e.g. filtering external ultraviolet light),and other functions.

FIG. 2 depicts illumination of transparent displays illuminated withexcitation light (e.g. ultraviolet light or infrared light) from lightsources (e.g. a projector or laser, depicted by device 20, in accordancewith embodiments. Substrate 14 may receive excitation light from a lightsource (e.g. projector or laser 20). The received excitation light maybe absorbed by light emitting material at substrate 14. When the lightemitting material receives the excitation light, the light emittingmaterial may emit visible light. Accordingly, images (e.g. circle 15 andtriangle 16) may be created at substrate 14 by selectively illuminatingsubstrate 14 with excitation light.

The excitation light may be ultraviolet light, in accordance withembodiments of the present disclosure. If the excitation light isultraviolet light, then when the light emitting material emits visiblelight in response to the ultraviolet light, a down-conversion physicalphenomenon occurs. Specifically, ultraviolet light has a shorterwavelength and higher energy than visible light. Accordingly, when thelight emitting material absorbs the ultraviolet light and emits lowerenergy visible light, the ultraviolet light is down-converted to visiblelight because the ultraviolet light's energy level goes down when it isconverted into visible light. In embodiments, the light emittingmaterial is fluorescent material.

The excitation light may be infrared light, in accordance withembodiments of the present disclosure. If the excitation light isinfrared light, then when the light emitting material emits visiblelight in response to the infrared light, an up-conversion physicalphenomenon occurs. Specifically, infrared light has a longer wavelengthand lower energy than visible light. Accordingly, when the lightemitting material absorbs the infrared light and emits higher energyvisible light, the infrared light is up-converted to visible lightbecause the infrared light's energy level goes up when it is convertedinto visible light. In embodiments, the light emitting material isfluorescent material. In the up-conversion physical phenomenon,absorption of more than one infrared light photon may be necessary forthe emission of every visible light photon. One having ordinary skill inthe art will appreciate that such a requirement, requiring absorption ofmultiple photons can make infrared light a less desirable option thanultraviolet light as an excitation light.

In embodiments illustrated in FIG. 1, the excitation light is output bydevice 20 including a projector. The projector may be a digitalprojector. In embodiments, the projector is a micro-mirror array (MMA)projector (e.g. a digital light processing (DLP) projector). A MMAprojector that outputs ultraviolet light may be similar to a MMAprojector that outputs visible light, except that the color wheel haslight filters that are tailored to the ultraviolet light spectrum. Inother embodiments, the projector is a liquid crystal display (LCD)projector. In embodiments, the projector may be a liquid crystal onsilicon (LCOS) projector. In embodiments, the projector may be an analogprojector (e.g. a slide film projector or a movie film projector). Oneof ordinary skill in the art would appreciate other types of projectorswhich may be used to project ultraviolet light on substrate 14.

FIG. 3 depicts an exemplary graphic projection upon a surface, inaccordance with the present disclosure. A radiation source 310 deliversan intense, collimated beam of invisible (or less visible) radiation.The radiation beam passes an optical image processor 330 and themodified radiation beam 350 is projected on to a fluorescence conversion(FC) displaying screen 380. A number of methods of image display aredisclosed. In a first exemplary method, expanded static radiation beamsare applied through an image processor 330 containing a matrix of on-offswitches (e.g., a matrix of tiny reflective mirrors) creating a darkimage, and a fluorescent visible image is created on the displayingscreen 380 through fluorescent conversion of the dark image. Staticimages are typically generated from a lookup table. In a secondexemplary method, a radiation beam is coupled with an image processor330 contains a two-dimensional beam scanner (e.g., galvanometer,acousto-optic light deflector (AOLD), and electro-optic light deflector(EOLD)). Electrical signals are applied to steer the radiation beam toilluminate a particular spot of the screen at a given time. Oneexemplary FC screen typically has the following structure: a layer 384contains fluorescent nano-particles or molecules attached to ordispersed in a uniform medium; a coating 388 reflects the visibleemission while transmitting the invisible radiation; and a substratelayer 390 that absorbs the remaining invisible radiation. Alternatively,it includes of a layer 384 containing fluorescent nano-particles ormolecules attached to or dispersed in a uniform medium; a coating 388absorbing the invisible radiation; and a visibly transparent substratelayer 390. Self-adhesive layer and protective layers such as a scratchresistance layer can also be added to the screen structure.

Two alternate schemes of FC are disclosed. FIG. 4 illustrates a schemefor utilizing excitation light to emit visible light from the HUD, inaccordance with the present disclosure. The first scheme, displayed inFIG. 4 is termed down-conversion, where the wavelength of the excitationlight is shorter than fluorescence wavelength. An energy level diagramillustrates the down-conversion molecule or nano-particle. The photon ofthe shorter wavelength excitation light has more energy and induces atransition 415 from a lower energy level 410 to a higher energy level420. The emission involves transition 425 associated with two energylevels with a smaller energy gap. The second scheme (not depicted) iscalled up-conversion, where excitation wavelengths are longer thanfluorescence wavelength. In the second case, two or more photons from alaser are necessary to excite the fluorescence particle in order toyield a visible fluorescence photon. The longer wavelength excitationlaser induces two transitions from a lower state to a higher energystate through an intermediate state. The emission involves transitionassociated with two energy levels with an energy gap that is smallerthan energy associated with two laser photons. A common approach for thefirst scheme is to apply a UV (or blue) light source with wavelengthshorter than 500 nm to excite the fluorescence molecules ornano-particles on the image screen. The UV sources include solid statelasers, semiconductor laser diodes, gas lasers, dye lasers, excimerlasers, and other UV light sources familiar to those skilled in the art.A common approach for the second scheme is to apply infrared lasers withwavelength longer than 700 nm to excite the fluorescence molecules orparticles on the Screen. The IR lasers include solid-state lasers,semiconductor laser diodes and other IR sources familiar to thoseskilled in the art. In both cases, excitation beam intensities aremodulated to yield visible fluorescence of varying intensity or grayscales.

A plurality of fluorescence materials is also disclosed. A commonproperty of these materials is that the size of the fluorescentparticles is very small. Typically, nano-particles or molecules withsize between 0.5 nm to 500 nm are preferred to have minimum scatteringeffect that reduces the visible transparency of the screen. Thesematerials fall into four categories: inorganic nano-meter sizedphosphors; organic molecules and dyes; semiconductor based nanoparticles; and organometallic molecules.

For down-conversions the following materials can be utilized to form FCdisplaying screen: 1. Inorganic or ceramic phosphors or nano-particles,including but not limited to metal oxides, metal halides, metalchalcoginides (e.g. metal sulfides), or their hybrids, such as metaloxo-halides, metal oxo-chalcoginides. These inorganic phosphors havefound wide applications in fluorescent lamps and electronic monitors.These materials can covert shorter wavelength photon (e.g. UV and blue)into longer wavelength visible light and can be readily deposited ondisplaying screens or dispersed in the screen. 2. Laser dyes and smallorganic molecules, and fluorescent organic polymers. These can also beused to convert shorter wavelength laser photon (e.g. UV and blue) intolonger wavelength visible light and can be readily deposited on adisplaying screen. Since they are in the molecular state in the solid,the screen transparency is maintained due to lack of particlescattering. 3. Semiconductor nano-particles, such as II-VI or III-Vcompound semiconductors, e.g. fluorescent quantum dots. Again, theiraddition in the screen does not affect the optical transparency 4.Organometallic molecules. The molecules include at least a metal centersuch as rare earth elements (e.g. Eu, Tb, Ce, Er, Tm, Pr, Ho) andtransitional metal elements such as Cr, Mn, Zn, Ir, Ru, V, and maingroup elements such as B, Al, Ga, etc. The metal elements are chemicallybonded to organic groups to prevent the quenching of the fluorescencefrom the hosts or solvents. Such organomettalic compounds filled screendoes not scatter light or affect the screen transparency either, unlikethe micro-sized particles.

Of the down-conversion FC materials or molecules mentioned above, thosethat can be excited by lasers of long wave UV (e.g. >300 nm) to blue(<500 nm), and yield visible light emission can be utilized byembodiments of the current disclosure. For example, the phosphors can beGarnet series of phosphors: (YmA1−m)3(AlnB1−n)5O12, doped with Ce; where0<=m, n<=1; A include other rare earth elements, B include B, Ga. Inaddition, phosphors containing metal silicates, metal borates, metalphosphates, and metal aluminates hosts are preferred in theirapplications to FC displays; In addition, nano-particulates phosphorscontaining common rare earth elements (e.g. Eu, Tb, Ce, Dy, Er, Pr, Tm)and transitional or main group elements (e.g. Mn, Cr, Ti, Ag, Cu, Zn,Bi, Pb, Sn, Tl) as the fluorescent activators, are also preferred intheir applications to FC displays. Finally, some undoped materials (e.g.Metal (e.g. Ca, Zn, Cd) tungstates, metal vanadates, ZnO, etc) are alsopreferred FC display materials.

The commercial laser dyes are another class of exemplary FC displaymaterials. A list of commercial laser dyes can be obtained from severallaser dye vendors, including Lambda Physik, and Exciton, etc. A partiallist of the preferred laser dye classes includes: Pyrromethene,Coumarin, Rhodamine, Fluorescein, other aromatic hydrocarbons and theirderivatives, etc. In addition, there are many polymers containingunsaturated carbon-carbon bonds, which also serve as fluorescentmaterials and find many optical and fluorescent applications. Forexample, MEH-PPV, PPV, etc have been used in opto-electronic devices,such as polymer light emitting diodes (PLED). Such fluorescent polymerscan be used directly as the fluorescent layer of the transparent 2-Ddisplay screen. In addition, the recently developed semiconductornanoparticles (e.g., quantum dots) are also a preferred LIF displaymaterials. The terms “semiconductor nanoparticles,” refers to aninorganic crystallite between 1 nm and 1000 nm in diameter, preferablybetween 2 nm to 50 nm. A semiconductor nano-particle is capable ofemitting electromagnetic radiation upon excitation (i.e., thesemiconductor nano-particle is luminescent). The nanoparticle can beeither a homogeneous nano-crystal, or includes of multiple shells. Forexample, it includes a “core” of one or more first semiconductormaterials, and may be surrounded by a “shell” of a second semiconductormaterial. The core and/or the shell can be a semiconductor materialincluding, but not limited to, those of the group II-VI (ZnS, ZnSe,ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, MgS, MgSe, MgTe, CaS, CaSe,CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, and the like) and III-V (GaN,GaP, GaAs, GaSb, InN, InP, InAs, InSb, and the like) and IV (Ge, Si, andthe like) materials, and an alloy or a mixture thereof.

Finally, fluorescent organometallic molecules containing rare earth ortransitional element cations are also utilized in the down-conversionfluorescent screens. Such molecules include a metal center of rare earthelements including Eu, Tb, Er, Tm, Ce protected with organic chelatinggroups. The metal center may also include transitional elements such asZn, Mn, Cr, Ir, etc and main group elements such as B, Al, Ga. Suchorganometallic molecules can readily be dissolved in liquid ortransparent solid host media and form a transparent fluorescent screenfor the disclosed 2-D transparent display with minimum light scattering.Some examples of such fluorescent organomettalic molecules include: 1.Tris(dibenzoylmethane)mono(phenanthroline)europium (III); 2.Tris(8-hydroxyquinoline)erbium; 3.Tris(1-phenyl-3-methyl-4-(2,2-dimethylpropan-1-oyl)pyrazolin-5-one)terbium(III); 4. Bis(2-methyl-8-hydroxyquinolato)zinc; 5.Diphenylborane-8-hydroxyquinolate.

Up-conversion phosphors are similar in chemical compositions as thedown-conversion fluorescent materials discussed. The up-conversionphosphors for the fluorescent conversion display also include thefollowing choice of materials or molecules: 1. Laser dyes, the organicsmall molecules that can be excited by the absorption of at least twoinfrared photons with emission of visible light. 2. Fluorescentpolymers, the class of polymers that can be excited by the absorption ofat least two infrared photons with emission of visible light 3.Inorganic or ceramic particles or nano-particles, including theconventional up-conversion phosphors (e.g. metal fluorides, metaloxides) that can be excited by the absorption of at least two infraredphotons with emission of visible light 4. Semiconductor particles,including nano-particles such as II-VI or III-V compound semiconductors,e.g. quantum dots, described in details in the “down-conversion”semiconductors above.

The fluorescent up-conversion inorganic phosphors include but are notlimited to metal oxides, metal halides, metal chalcoginides (e.g.sulfides), or their hybrids, such as metal oxo-halides, metaloxo-chalcoginides. They are usually doped with rare earth elements (e.g.Yb<3+>, Er<3+>, Tm<3+>. Some host examples include, but are not limitedto: NaYF4, YF3, BaYF5, LaF3, La2MoO8, LaNbO4, LnO2S; where Ln is therare earth elements, such as Y, La, Gd). These FC displaying materialsmay be used to form a variety of FC displaying objects. These objectsinclude: screens, plates, windows, walls, billboards, and otherdisplaying surfaces. There are several means to incorporate thesefluorescent molecules or materials onto a displaying surface: 1. Theycan be dissolved (organic dyes) or dispersed (inorganic particles) intosolvents (water or organic solvents). The liquid fluorescent formula canbe either coated onto a surface and form a solid film or coating afterdrying, or they can be sandwiched between two surfaces in liquid form.2. They can be dissolved (organic dyes) or dispersed (inorganicparticles) into solid hosts, such as glasses, polymers, gels,inorganic-organic hybrid hosts, cloths, papers, films, tapes, etc. andturn the solid into a fluorescent object for laser display. 3. Someobjects (e.g. cloths, paper, tapes, fluorescent polymers) may alreadycontain fluorescent molecules or luminescent functional groups. In thatcircumstance, they can be directly used as laser display objects.

Returning to the exemplary embodiment illustrated in FIG. 2, anexcitation light is output from device 20, in this example, a laser. Theintensity and/or movement of a laser beam output from device 20 may bemodulated to create an image in substrate 14. In down-conversionembodiments, the output from the laser may be ultraviolet light. Inup-conversion embodiments, the output from the laser may be infraredlight.

FIG. 2 is an example diagram of light emitting material (e.g. lightemitting particles 22) dispersed in a substantially transparentsubstrate, according to embodiments. When excitation light is absorbedby the light emitting particles 22, the light emitting particles emitvisible light. Accordingly, in down-conversion embodiments, whenultraviolet light is absorbed by light emitting particles 22, visiblelight is emitted from the light emitting particles. Likewise, inup-conversion embodiments, when infrared light is absorbed by lightemitting particles 22, visible light is emitted from the light emittingparticles.

In some exemplary embodiments, more than one projector or laser may beutilized for illumination. For example, a first projector may be usedfor excitation of light emitting material which emits a first color anda second projector may be used for excitation of light emitting materialwhich emits a second color. Use of more than one projector may increasethe amount of excitation light which is absorbed by the light emittingmaterial. By increasing the amount of excitation light absorbed, theamount of visible light emitted from the light emitting material may beincreased. The greater the amount of visible light emitted, the brighterthe display. In embodiments, a first projector may be designated forcausing emission of red light, a second projector may be designated forcausing emission of green light, and a third projector may be designatedfor causing emission of blue light. However, other configurations can beappreciated. For example, use of two projectors, four projectors,projectors which cause emission of primary colors, projectors whichcause the emission of non-primary colors, and substituting lasers forprojectors in similar configurations are appreciated.

FIG. 2 illustrates light emitting material, including light emittingparticles 22, dispersed in a substantially transparent substrate,according to embodiments of the disclosure. These light emittingparticles 22 can be substantially similar particles throughout, or, asdepicted in FIG. 2, the particles can vary in composition. Whenexcitation light is absorbed by the light emitting particles 22, theparticles emit visible light. Accordingly, in down-conversionembodiments, when ultraviolet light is absorbed by light emittingmaterials, visible light is emitted from the light emitting materials.Likewise, in up-conversion embodiments, when infrared light is absorbedby light emitting materials, visible light is emitted from the lightemitting materials. In embodiments, each of light emitting materials maybe a different type of light emitting material, which emits a differentrange of wavelengths of visible light in response to a different rangeof wavelengths of excitation light (e.g. ultraviolet or infrared light).

Light emitting particles 22 may be dispersed throughout substrate 14. Inthe alternative, as depicted in FIG. 2, the particles may be disposed ona surface of substrate 14. Light emitting particles 22 may be integratedinto substrate 14 by being coated on substrate 14. Light emittingmaterial may be fluorescent material, which emits visible light inresponse to absorption of electromagnetic radiation (e.g. visible light,ultraviolet light, or infrared light) that is a different wavelengththan the emitted visible light. The size of the particles may be smallerthan the wavelength of visible light, which may reduce or eliminatevisible light scattering by the particles. Examples of particles thatare smaller than the wavelength of visible light are nanoparticles ormolecules. According to embodiments, each of the light emittingparticles has a diameter that is less than about 400 nanometers.According to embodiments, each of the light emitting particles has adiameter that is less than about 300 nanometers. According toembodiments, each of the light emitting particles has a diameter that isless than about 200 nanometers. According to embodiments, each of thelight emitting particles has a diameter that is less than about 100nanometers. According to other embodiments, each of the light emittingparticles has a diameter that is less than about 50 nanometers. Thelight emitting particles may be individual molecules.

Other methods can be appreciated for integrating light emittingmaterials on a surface of substrate 14. Similar to embodimentsillustrated in example FIG. 2, each of the light emitting materials maybe a different type of light emitting material, which emit a differentrange of wavelengths of visible light in response to a different rangeof wavelengths of excitation light (e.g. ultraviolet or infrared light).Light emitting material may be fluorescent material, which emits visiblelight in response to absorption of electromagnetic radiation (e.g.visible light, ultraviolet light, or infrared light) that is a differentwavelength than the emitted visible light. Light emitting material mayinclude light emitting particles.

In DLP or MMA projector embodiments, the wavelength of ultraviolet lightemitted from a DLP projector can be modulated using a color wheel withspecific ultraviolet pass filters. Similar modulation techniques may beutilized in other projector embodiments and laser embodiments. Inembodiments, multiple projectors and multiple lasers may be utilized,each being associated with a specific ultraviolet wavelength range toexcite a specific type of light emitting particle, to output a specificcolor of light.

FIG. 5 depicts an exemplary arrangement of light emitting particles upona substrate, in accordance with the present disclosure. FIG. 5 is anexample diagram of different types of light emitting particles,associated with different visible colors, which may be coated on regionsof substrate 14 (e.g. stripe region 32, stripe region 34, and striperegion 36) in a substantially transparent substrate. In embodiments,substrate 14 may include different regions in which different types oflight emitting particle are dispersed. For example, a first type oflight emitting particle (e.g. a light emitting particle associated withred light) may be dispersed in stripe region 32, a second type of lightemitting particle (e.g. a light emitting particle associated with greenlight) may be dispersed in stripe region 34, and a third type of lightemitting particle (e.g. a light emitting particle associated with bluelight) may be dispersed in stripe region 36. Stripe regions may beformed in stripes (i.e. rows). In the alternative, stripe section couldbe subdivided into a block matrix pattern with alternating colors ineach of the blocks. In the alternative to the stripe regions beingcoated on the surface of substrate 14, the stripe regions can bedispersed through the substrate.

A projector or laser (e.g. projector or laser 20) may use an excitationlight wavelength range that excites all of the different types of lightemitting particles and selectively illuminates different colors byspatial modulation of the excitation light. For example, in example FIG.5, to emit green visible light in a given region of substrate 14, aprojector or laser may illuminate a portion of stripe region 34 (e.g.which includes light emitting particles associated with green light). Inembodiments that spatially separate the different types of lightemitting particles, it is not necessary for the excitation light sourceto modulate the wavelength of the excitation light to create differentcolors, because color may be selected by the spatial modulation of theexcitation light.

In embodiments, excitation light projected on substrate 14 of FIG. 5 canbe wavelength modulated to cause emission of different colors.Accordingly, it may not be necessary to spatially modulate theexcitation light. When the excitation light projected on substrate 14 iswavelength modulated, only the regions (e.g. stripes or pixels) whichare sensitive to a particular wavelength will be illuminated. Inembodiments, excitation light can be both spatially modulated andwavelength modulated.

FIG. 6 illustrates different types of light emitting materials layeredon a substrate, in accordance with the present disclosure. Inembodiments, the light emitting materials 92, 94, 96, are substantiallytransparent to light, except light with specific wavelength ranges whichare absorbed and are different for each of the different light emittingmaterials 92, 94, and 96. Accordingly, in embodiments, the excitationlight projected on substrate 14 does not need to be spatially modulated.Further, the layers may be coated on the substrate with differentthicknesses. By coating the different light emitting materials 92, 94,and 96 with different thicknesses, the responsiveness to excitationlight of a particular type of material can be controlled. For example,it may be desirable to balance the emission of different primary colors,since different light emitting materials may illuminate the differentcolors at different intensities from the same amount of absorbed light.

In embodiments, a screen is pixelated using RGB elements. Each pixelincludes 3 portions for RGB respectively. A single projective UV beamcan be illuminated onto the pixelated screen. To get various mixtures ofRGB for different colors, the same UV projective beam on a pixel may beshifted to cover a certain amount of areas of the RGB elements within apixel. Accordingly, only one projective beam is necessary to generatethe full color projective image. The color balance of the RGB for apixel can be calculated and converted into the right area of RGBelements on the screen, the beam can then be shifted to cover the rightrelative area percentage of each RGB elements to display the right coloron the pixel.

FIG. 7 is an exemplary diagram of the excitation and emissionrelationships of different light emitting materials, in accordance withe the present disclosure. Example region 48 illustrates theexcitation/emission cross-section of a first type of light emittingmaterial. Example region 46 illustrates the excitation/emissioncross-section of a second type of light emitting material. Exampleregion 50 illustrates the excitation/emission cross-section of a thirdtype of light emitting material. However, it will be appreciated thatmany exemplary excitation/emission cross-sections are envisioned,including embodiments wherein a single excitation frequency range iscapable of creating a plurality of emission ranges, or in the converse,wherein a plurality of excitation frequency ranges can alternativelycreate the same or overlapping emission ranges.

Each of the plurality of light emitting particles may have a diameterless than about 500 nanometers. Each of the plurality of light emittingparticles may have a diameter less than about 400 nanometers. Each ofthe plurality of light emitting particles may have a diameter less thanabout 300 nanometers. Each of the plurality of light emitting particlesmay have a diameter less than about 200 nanometers. Each of theplurality of light emitting particles may have a diameter less thanabout 100 nanometers. Each of the plurality of light emitting particlesmay have a diameter less than about 50 nanometers. Each of the pluralityof light emitting particles may be an individual molecule. Each-of theplurality of light emitting particles may be an individual atom.

The above embodiments describe fluorescent particles as a method todisplay graphical images upon an otherwise substantially transparentwindscreen of a vehicle. However, those having skill in the art willappreciate that other methods are known to project graphical images upona display that can be otherwise substantially transparent. FIG. 8 is anexemplary diagram of a pattern of microstructures dispersed in asubstantially transparent or translucent substrate, in accordance withthe present disclosure. Microstructures 26 are selectively dispersed insubstrate 14 in regions. The width of the regions of microstructures 26may be in a range of about 1 nanometer to about 10 millimeters. Theregions of microstructures 26 form a pattern (e.g. a blind or a grid),such that there is limited cross-section of viewer's 10 light paths 30with the microstructures 26. In embodiments, the pattern is repetitive.The fill-factor of the pattern may be in a range of about 0.01% to about99%. However, the light path 28 from device 20 may be at an angle withthe regions of microstructures 26 to maximize the cross-section with themicrostructures 26, increasing the scattering of a visible image fromdevice 20 to increase illumination of the visible image on substrate 14.The pitch of the regions of microstructures 26 may be in a range ofabout 1 nanometer to about 10 millimeters. The thickness of the regionsof microstructures 26 may be in a range of about 1 micrometer to about10 millimeters. The thickness of the regions of microstructures 26 maybe smaller than the width and/or pitch of the regions of microstructures26.

FIG. 9 is an example diagram of a pattern of microstructures disposed ona surface of a substantially transparent or translucent substrate,similar to FIG. 8, in accordance with the present disclosure.Microstructures 38 may be coated in regions on substrate 14. The regionsof microstructures 38 form a blind, such that there is limited (e.g.minimized) cross-section of viewer's 10 light paths 30 withmicrostructures 38. However, the light path 28 from device 20 may be atan angle with the regions of microstructures 38 to maximize thecross-section with the microstructures, increasing the scattering of avisible image from device 20 to increase illumination of the visibleimage on substrate 14. In embodiments, the cross-section with thesurface of substrate 14 of each element of pattern of microstructures 38is less than the depth of the pattern substantially perpendicular tosubstrate 14, which may increase the transparency of substrate 14.

FIG. 10 is an example diagram of an angled pattern of microstructuresdispersed in a substantially transparent or translucent substrate,similar to FIG. 8, in accordance with the present disclosure. Slantedregions of microstructures 39 are formed in substrate 14. The angle ofthe slanted regions of microstructures 39 affects the cross-sectionalarea of both the viewer's 10 light path 30 and light path 28 ofprojector 18. By increasing the cross-section of light path 28,increased scattering of viewable images may be accomplished, therebyincreasing the illumination at substrate 14 of the viewable image. Inembodiments, slanted regions of microstructures can also be accomplishedby coating the regions of microstructures on substrate 14.

Embodiments relate to transparent projective displays with partially ordirectional transparent screens. In this display, a regular full coloroptical projector (or monochromatic scanner) may be applied to apartially or directional transparent screen to display an optical image.A partially or directional transparent screen may have dualcharacteristics. First, a partially or directional transparent screenmay be sufficiently transparent to allow visual penetration of ambientlight. Second, a partially or directional transparent screen may befilled or coated with reflective small particles or micro-structuresthat will deflect or scatter the projected optical images as a displayscreen. Such particles and micro-structures will not completely blockthe visible view through windows.

There are several approaches to prepare a partially or directionaltransparent screen, in accordance with embodiments. A transparent ortranslucent glass or plastic plate may be filled by fine particles from1 nanometer to 10 micrometers. A transparent or translucent glass orplastic plate may be coated by fine particles from 1 nanometer to 10micrometers. A transparent or translucent thin glass sheet or plasticfilm may be filled by fine particles from 1 nanometer to 10 micrometers.A transparent or translucent thin glass sheet or plastic film may becoated by fine particles from 1 nanometer to 10 micrometers. A diffusivegrid may be embedded in or patterned on the surfaces of transparent ortranslucent glass or plastics sheets.

Both organic and inorganic particles or pigments may be applied in or ona partially or directional transparent screen. Some examples includetitanium oxides, silica, alumna, latex, polystyrene particles. Inembodiments, the size of the particles may range from about 1 nanometerto about 10 micrometers. In embodiments, the size of the particlesranges from about 10 nanometers to about 1 micrometers. These lightscattering materials can be evenly dispersed into the glass or plastichosts at appropriate concentrations, or they can be coated on the glassor plastic surfaces with an appropriate thickness. A protective overcoator another layer of host can be applied on the particle coat to preventthe damage to the surface on physical touch.

The glass for a partially or directional transparent screen may includeinorganic solids which are transparent or translucent to the visiblelight. Examples of such inorganic solids are oxides and halides. Theglass may include silicates, borosilicate, lead crystal, alumina,silica, fused silica, quartz, glass ceramics, metal fluorides, and othersimilar materials. These types of glass may be used as the window inrooms, buildings, and/or moving vehicles. Plastics for a partially ordirectional transparent screen may include organic and polymeric solids,which are transparent or translucent to the visible light.Thermoplastics for fluorescent screens may include special thermosetsolids, such as transparent gels. Some examples of the plastics includepolyacrylic, polycarbonate, polyethylene, polypropylene, polystyrene,PVC, silicone, and other similar materials. Micro-structures may beintegrated into the screen plate or on the surface, to deflect theprojected image from an angle, while allowing the substantial visibletransparency at normal viewing angles. An opaque diffusive grid may beembedded in the thin glass or plastic sheet. The area of the lightscattering grid from a viewer who stands in front of the screen issubstantially smaller than that from the image projector.

Directional transparent screen structures, in accordance withembodiments, may offer many advantages. Directional transparent screenstructures may be substantially transparent to the viewer normal orslightly off the normal angle to the screen. Directional transparentscreen structures may have a high reflectance or deflection to theprojection image at a tilting angle to the screen. A columnartransparent region may be solid opaque to the projection image at thetilting angle. Such strong image scattering may enhance the contrast ofthe projection images on the display window, while not blocking thedirect view normal to the screen. Directional transparent screenstructures may be useful in automobiles, where the driver's view istypically normal to the windshield glass. In embodiments, opaque columnstrespass the depth of a transparent host glass or plastics. Inembodiments, the sizes and the density of the microstructures on thescreen may be varied to adjust to transparency of normal view andreflectance image contrast. The depth of the screen and the projectionangle may also be varied to tune the contrast and transparency.

In embodiments, the surfaces of the screen may be patterned to variousunisotropic structures to function as an “unisotropic” screen. Forexample, a pattern of overcoat with certain thickness (e.g. 10 nanometerto 1 millimeter) can be applied to the screen surfaces, by variousprinting, stamping, photolithographic methods, micro-contact printing,and other similar methods. Such printing may form a pattern of very finescattering features and structures on the surface of the screen, whichmay allow for angular scattering and displaying of projected images,while allowing a substantially direct view through the screen at asubstantially normal angle to the screen.

FIG. 11 illustrates an exemplary embodiment of a two-dimensional lightbeam based FC display subsystem, in accordance with the presentdisclosure. The excitation source 610 preferably passes through a set ofbeam-diameter control optics 612 and a 2-D acousto-optical scanner 615.A scan control interface unit 620 coordinates the functions of a DirectDigital Synthesizer 622, an RF amplifier 625 and Beam-Diameter ControlOptics 612. The processes image beam is projected on to a FC screenthrough an angle extender 650. In order to deliver consistent and stableimage on the FC screen, a beam splitter deflects the image into aposition sensitive detector (PSD) 635 and processed through positionsensitive detector processor 630, feedback to scan control interfaceunit 620. The close-loop image feedback formed by 632, 635, 630 and 620is incorporated to maintain position accuracy and pointing stability ofthe laser beam.

It will be apparent to those having ordinary skill of the art that manyvariations and modifications can be made to the system, method, materialand apparatus of FC based display disclosed herein without departingfrom the spirit and scope of the present disclosure. It is thereforeintended that the present disclosure cover the modifications andvariations of this disclosure provided that they come within the scopeof the appended claims and their equivalents,

In embodiments, a UV lamp or lower wavelength visible lamp is used inthe projector, which may be a liquid crystal display (LCD) or DLP. Theprojector may interface to a computer, PDA, DVD, VCR, TV, or otherinformation input devices. In embodiments, a fluorescent screen may be atransparent or translucent glass or plastic plate filled by fluorescentorganic dyes or inorganic phosphors.

Transparent or substantially transparent displays may have manyapplications. For example, transparent or substantially transparentdisplays may display an image on a transparent or translucent window ofmoving vehicles, such as automobiles, motorcycles, aircrafts, and boats;the image may be information on the conditions of the vehicles.Directions (e.g. GPS map), that are currently displayed on the dashboardelectronic display, may be projected onto the windows (e.g. front glass,wind shields) of the vehicle. Drivers do not have to turn their eyesaway from the road to view the vehicle conditions and/or directions.

In embodiments, a fluorescent screen may be a transparent or translucentglass or plastic plate filled by fluorescent organic dyes or inorganicphosphors. In embodiments, a fluorescent screen may be a transparent ortranslucent glass or plastic plate coated by fluorescent organic dyes orinorganic phosphors. In embodiments, a fluorescent screen may be atransparent or translucent thin glass sheet or plastic film filled byfluorescent organic dyes or inorganic phosphors. In embodiments, afluorescent screen may be a transparent or translucent thin glass sheetor plastic film coated by fluorescent organic dyes or inorganicphosphors. The glass for the fluorescent screen may include inorganicsolids which are transparent or translucent to the visible light.Examples of such inorganic solids are oxides and halides. The glass mayinclude silicates, borosilicate, lead crystal, alumina, silica, fusedsilica, quartz, glass ceramics, metal fluorides, and other similarmaterials. These types of glass may be used as the window in rooms,buildings, and/or moving vehicles. Plastics for fluorescent screens mayinclude organic and polymeric solids, which are transparent ortranslucent to the visible light. Thermoplastics for fluorescent screensmay include special thermoset solids, such as transparent gels. Someexamples of the plastics include polyacrylic, polycarbonate,polyethylene, polypropylene, polystyrene, PVC, silicone, and othersimilar materials.

Glass and plastic may be turned into fluorescent projective displays, bycombining them with fluorescent dyes. Fluorescent dyes are organicmolecules or materials that can absorb a higher energy photon and emitlower energy photon. To emit visible light, such molecules may absorb UVlight or lower wavelength visible (e.g. violet or blue) light, in thetypical wavelength range of 190 nm to 590 nm or in the wavelength rangeof 300 nm to 450 nm. Some examples of the fluorescent dyes include (butare not limited to) commercial dye molecules from various dye vendors,including Lambda Physik and Exciton. Fluorescent dyes that may be usedin a transparent display include Pyrromethene, Coumarin, Rhodamine,Fluorescein, and other aromatic hydrocarbons and their derivatives. Inaddition, there are many polymers containing unsaturated bonds, whichcan be fluorescent materials that may be used in a transparent display.For example, some of them (MEH-PPV, PPV, etc) have been used inoptoelectronic devices, such as polymer light emitting diodes (PLED).

Glass or plastics may be turned into a fluorescent projective display,by combining them with phosphor materials. The down-conversion phosphorsinclude inorganic or ceramic particles or nano-particles, including butnot limited to metal oxides, metal halides, metal chalcoginides (e.g.metal sulfides), or their hybrids, such as metal oxo-halides and metaloxo-chalcoginides. These inorganic phosphors have found wideapplications in fluorescent lamps and electronic monitors. They may beapplied in converting shorter wavelength projective light (e.g. UV andblue) into higher wavelength visible light. They may be dispersed orcoated to the transparent screen or window and excited by correspondingshorter wavelength projective light to display a visible image.

Fluorescent phosphors or dye molecules that can be excited into visiblelight by projective light ranging from ultraviolet light (e.g.wavelength greater than 240 nanometer) to blue (e.g. less than 500nanometer). Lamps for projectors may emit light in this range ofwavelengths. Such lamps are commercially available (e.g. those used forskin-tanning purposes). They can also be halogen lamps, specialincandescent lamps, and arc vapor lamps (e.g. mercury, xenon, deuteron,etc). Such lamps may contain phosphors to convert shorter wavelength UVto longer wavelength UV.

Phosphors containing metal oxide hosts (e.g. metal silicates, metalborates, metal phosphates, metal aluminates); metal oxohalides,oxosulfides, metal halides, metal sulfides, and chalcoginides may beapplied to the projective fluorescence displays. One example ofphosphors that may be used in fluorescent displays includes the Garnetseries of phosphors: (YmA1−m)3(AlnB1−n)5O12, doped with Ce; where 0<=m,n<=1; A includes other rare earth elements, B include B and/or Ga. Inaddition, phosphors containing common rare earth elements (e.g. Eu, Tb,Ce, Dy, Er, Pr, and/or Tm) and transitional or main group elements (e.g.Mn, Cr, Ti, Ag, Cu, Zn, Bi, Pb, Sn, and/or Tl) as the fluorescentactivators may be applied to projective fluorescence displays. Someundoped materials (e.g. metal, Ca, Zn, Cd, tungstates, metal vanadates,and ZnO) are also luminescent materials and may be applied in projectivefluorescent displays.

The organic dyes and inorganic phosphors may be filled in or coated onthe hosts of glass or plastics to prepare a fluorescent transparentscreen. The dye molecules, if dissolved in the hosts, will not scatterthe visible light, although it may absorb some visible light and addsome color tint to the hosts. In contrast, larger phosphor particleswill scatter visible light, which will affect the optical transparencyof the hosts. Embodiments relate to different approaches to reduce thescattering of the phosphor particles to visible light. In embodiments,the size of the phosphor particles is reduced. In embodiments, theconcentration of phosphor particles is reduced and evenly dispersed inthe host. In embodiments, hosts are chosen with refractive indexes closeto those of the phosphors to reduce the scattering or phosphors arechosen with refractive indexes close to those of the hosts.

Known vehicle systems utilize sensors, inputs from various devices, andon-board or remote processing to establish information regarding theenvironment surrounding the vehicle. For instance, adaptive cruisecontrol systems utilize sensors such as radar devices to track objectssuch as a target vehicle in front of the host vehicle and adjust vehiclespeed in accordance with a range and a change in range sensed withrespect to the target vehicle. Collision avoidance or preparationsystems analyze objects sensed in the path of the vehicle and takeactions based upon a perceived probability of collision between thesensed object and the vehicle. Lane keeping systems utilize availablesensor and data to maintain a vehicle within lane markings.

FIG. 12 shows a schematic diagram of the vehicle 710 system which hasbeen constructed with a target tracking system, in accordance with thepresent disclosure. The exemplary vehicle includes a passenger vehicleintended for use on highways, although it is understood that thedisclosure described herein is applicable on any vehicle or other systemseeking to monitor position and trajectory of remote vehicles and otherobjects. The vehicle includes a control system containing variousalgorithms and calibrations executed at various times. The controlsystem is preferably a subset of an overall vehicle control architecturewhich is operable to provide coordinated vehicle system control. Thecontrol system is operable to monitor inputs from various sensors,synthesize pertinent information and inputs, and execute algorithms tocontrol various actuators to achieve control targets, including suchparameters as collision avoidance and adaptive cruise control. Thevehicle control architecture includes a plurality of distributedprocessors and devices, including a system controller providingfunctionality such as antilock brakes, traction control, and vehiclestability.

Referring to FIGS. 12-14, the exemplary vehicle 710 includes a controlsystem having an observation module 722, a data association andclustering (DAC) module 724 that further includes a Kalman filter 724A,and a track life management (TLM) module 726 that keeps track of a tracklist 726A including of a plurality of object tracks. More particularly,the observation module includes sensors 714 and 716, their respectivesensor processors, and the interconnection between the sensors, sensorprocessors, and the DAC module.

The exemplary sensing system preferably includes object-locating sensorsincluding at least two forward-looking range sensing devices 714 and 716and accompanying subsystems or processors 714A and 716A. Theobject-locating sensors may include a short-range radar subsystem, along-range radar subsystem, and a forward vision subsystem. Theobject-locating sensing devices may include any range sensors, such asFM-CW radars, (Frequency Modulated Continuous Wave), pulse and FSK(Frequency Shift Keying) radars, and Lidar (Light Detection and Ranging)devices, and ultrasonic devices which rely upon effects such asDoppler-effect measurements to locate forward objects. The possibleobject-locating devices include charged-coupled devices (CCD) orcomplementary metal oxide semi-conductor (CMOS) video image sensors, andother known camera/video image processors which utilize digitalphotographic methods to ‘view’ forward objects. Such sensing systems areemployed for detecting and locating objects in automotive applications,useable with systems including, e.g., adaptive cruise control, collisionavoidance, collision preparation, and side-object detection. Theexemplary vehicle system may also include a global position sensing(GPS) system.

These sensors are preferably positioned within the vehicle 710 inrelatively unobstructed positions relative to a view in front of thevehicle. It is also appreciated that each of these sensors provides anestimate of actual location or condition of a targeted object, whereinthe estimate includes an estimated position and standard deviation. Assuch, sensory detection and measurement of object locations andconditions are typically referred to as “estimates.” It is furtherappreciated that the characteristics of these sensors are complementary,in that some are more reliable in estimating certain parameters thanothers. Conventional sensors have different operating ranges and angularcoverages, and are capable of estimating different parameters withintheir operating range. For example, radar sensors can usually estimaterange, range rate and azimuth location of an object, but is not normallyrobust in estimating the extent of a detected object. A camera withvision processor is more robust in estimating a shape and azimuthposition of the object, but is less efficient at estimating the rangeand range rate of the object. Scanning type Lidars perform efficientlyand accurately with respect to estimating range, and azimuth position,but typically cannot estimate range rate, and is therefore not accuratewith respect to new object acquisition/recognition. Ultrasonic sensorsare capable of estimating range but are generally incapable ofestimating or computing range rate and azimuth position. Further, it isappreciated that the performance of each sensor technology is affectedby differing environmental conditions. Thus, conventional sensorspresent parametric variances, but more importantly, the operativeoverlap of these sensors creates opportunities for sensory fusion.

Each object-locating sensor and subsystem provides an output includingrange, R, time-based change in range, R_dot, and angle, Θ, preferablywith respect to a longitudinal axis of the vehicle, which can be writtenas a measurement vector (O), i.e., sensor data. An exemplary short-rangeradar subsystem has a field-of-view (FOV) of 160 degrees and a maximumrange of thirty meters. An exemplary long-range radar subsystem has afield-of-view of 17 degrees and a maximum range of 220 meters. Anexemplary forward vision subsystem has a field-of-view of 45 degrees anda maximum range of fifty (50) meters. For each subsystem thefield-of-view is preferably oriented around the longitudinal axis of thevehicle 710. The vehicle is preferably oriented to a coordinate system,referred to as an XY-coordinate system 720, wherein the longitudinalaxis of the vehicle 710 establishes the X-axis, with a locus at a pointconvenient to the vehicle and to signal processing, and the Y-axis isestablished by an axis orthogonal to the longitudinal axis of thevehicle 710 and in a horizontal plane, which is thus parallel to groundsurface.

FIG. 14 depicts an exemplary data fusion process, in accordance with thepresent disclosure. As shown in FIG. 14, the illustrated observationmodule includes first sensor 714 located and oriented at a discretepoint A on the vehicle, first signal processor 714A, second sensor 716located and oriented at a discrete point B on the vehicle, and secondsignal processor 716A. The first processor 714A converts signals(denoted as measurement O_(A)) received from the first sensor 714 todetermine range (RA), a time-rate of change of range (R_dotA), andazimuth angle (ΘA) estimated for each measurement in time of targetobject 730. Similarly, the second processor 716A converts signals(denoted as measurement O_(B)) received from the second sensor 716 todetermine a second set of range (RB), range rate (R_dotB), and azimuthangle (ΘB) estimates for the object 730.

The exemplary DAC module 724 includes a controller 728, wherein analgorithm and associated calibration (not shown) is stored andconfigured to receive the estimate data from each of the sensors A, B,to cluster data into like observation tracks (i.e. time-coincidentobservations of the object 730 by sensors 714 and 716 over a series ofdiscrete time events), and to fuse the clustered observations todetermine a true track status. It is understood that fusing data usingdifferent sensing systems and technologies yields robust results. Again,it is appreciated that any number of sensors can be used in thistechnique. However, it is also appreciated that an increased number ofsensors results in increased algorithm complexity, and the requirementof more computing power to produce results within the same time frame.The controller 728 is housed within the host vehicle 710, but may alsobe located at a remote location. In this regard, the controller 728 iselectrically coupled to the sensor processors 714A, 716A, but may alsobe wirelessly coupled through RF, LAN, infrared or other conventionalwireless technology. The TLM module 726 is configured to receive andstore fused observations in a list of tracks 726A.

Sensor registration, or “alignment” of sensors, in multi-target tracking(‘MTT’) fusion, involves determining the location, orientation andsystem bias of sensors along with target state variables. In a generalMTT system with sensor registration, a target track is generated duringvehicle operation. A track represents a physical object and includes anumber of system state variables, including, e.g., position andvelocity. Measurements from each individual sensor are usuallyassociated with a certain target track. A number of sensor registrationtechniques are known in the art and will not be discussed in detailherein.

The schematic illustration of FIG. 12 includes the aforementionedobject-locating sensors 714 and 716 mounted on the exemplary vehicle atpositions A and B, preferably mounted at the front of the vehicle 710.The target object 730 moves away from the vehicle, wherein t1, t2, andt3 denote three consecutive time frames. Lines ra1-ra2-ra3, rf1-rf2-rf3,and rb1-rb2-rb3 represent, respectively, the locations of the targetmeasured by first sensor 714, fusion processor, and second sensor 716 attimes t1, t2, and t3, measured in terms of O_(A)=(R_(A),R_dot_(A),Θ_(A))and _(B)=(R_(B),R_,Θ_(B)), using sensors 714 and 716, located at pointsA, B.

A known exemplary trajectory fusing process, for example as disclosed inU.S. Pat. No. 7,460,951, entitled SYSTEM AND METHOD OF TARGET TRACKINGUSING SENSOR FUSION, and incorporated herein by reference, permitsdetermining position of a device in the XY-coordinate system relative tothe vehicle. The fusion process includes measuring the target object 730in terms of O_(A)=(R_(A),R_dot_(A),Θ_(A)) andO_(B)=(R_(B),R_dot_(B),Θ_(B)), using sensors 714 and 716, located atpoints A, B. A fused location for the target object 730 is determined,represented as x=(RF,R_dotF, ΘF, Θ_dotf), described in terms of range,R, and angle, Θ, as previously described. The position of forward object730 is then converted to parametric coordinates relative to thevehicle's XY-coordinate system. The control system preferably uses fusedtrack trajectories (Line rf1, rf2, rf3), including a plurality of fusedobjects, as a benchmark, i.e., ground truth, to estimate true sensorpositions for sensors 714 and 716. As shown in FIG. 12, the fusedtrack's trajectory is given by the target object 730 at time series t1,t2, and t3. Using a large number of associated object correspondences,such as {(ra1, rf1, rb1), (ra2, rf2, rb2), (ra3, rf3, rb3)} truepositions of sensors 714 and 716 at points A and B, respectively, can becomputed to minimize residues, preferably employing a knownleast-squares calculation method. In FIG. 12, the items designated asra1, ra2, and ra3 denote an object map measured by the first sensor 714.The items designated as rb1, rb2, and rb3 denote an object map observedby the second sensor 716.

FIG. 13 depicts an information flow utilized in creating a track list,in accordance with the present disclosure. In FIG. 13, referenced tracksare preferably calculated and determined in the sensor fusion block 728of FIG. 14, described above. The process of sensor registration includesdetermining relative locations of the sensors 714 and 716 and therelationship between their coordinate systems and the frame of thevehicle, identified by the XY-coordinate system. Registration for singleobject sensor 716 is now described. All object sensors are preferablyhandled similarly. For object map compensation, the sensor coordinatesystem or frame, i.e. the UV-coordinate system, and the vehiclecoordinate frame, i.e. the XY-coordinate system, are preferably used.The sensor coordinate system (u, v) is preferably defined by: (1) anorigin at the center of the sensor; (2) the v-axis is along longitudinaldirection (bore-sight); and (3) a u-axis is normal to v-axis and pointsto the right. The vehicle coordinate system, as previously described, isdenoted as (x,y) wherein x-axis denotes a vehicle longitudinal axis andy-axis denotes the vehicle lateral axis.

The locations of track (x) can be expressed in XY-coordinate system as(r). Sensor measurement (o) can be expressed in UV-coordinate as (q).The sensor registration parameters (a) include of rotation (R) andtranslation (r0) of the UV-coordinate system.

FIG. 15 depicts an exemplary dataflow enabling joint tracking and sensorregistration, in accordance with the present disclosure. The method isinitiated upon reception of sensor data. A data association module willmatch the sensor data with the predicted location of a target. The jointtracking and registration module combines the previous estimation (i.e.,a priori) and new data (i.e., matched measurement-track pairs), andupdates the target tracks estimation and sensor registration data in thedatabase. The time propagation process module predicts the target tracksor sensor registration parameters in the next time cycle based on thehistorical sensor registration, tracks and current vehicle kinematicsvia a dynamics model. The sensor registration parameters are usuallyassumed to be substantially constant over time. Confidence of theregistration parameters accumulates over time. However, a prioriinformation about registration will be reset to zero when a significantsensor registration change is detected (e.g., vehicle collision).

Object tracks can be utilized for a variety of purposes includingadaptive cruise control, wherein the vehicle adjusts speed to maintain aminimum distance from vehicles in the current path, as described above.Another similar system wherein object tracks can be utilized is acollision preparation system (CPS), wherein identified object tracks areanalyzed in order to identify a likely impending or imminent collisionbased upon the track motion relative to the vehicle. A CPS warns thedriver of an impending collision and reduces collision severity byautomatic braking if a collision is considered to be unavoidable. Amethod is disclosed for utilizing a multi-object fusion module with aCPS, providing countermeasures, such as seat belt tightening, throttleidling, automatic braking, air bag preparation, adjustment to headrestraints, horn and headlight activation, adjustment to pedals or thesteering column, adjustments based upon an estimated relative speed ofimpact, adjustments to suspension control, and adjustments to stabilitycontrol systems, when a collision is determined to be imminent.

FIG. 16 schematically illustrates an exemplary system whereby sensorinputs are fused into object tracks useful in a collision preparationsystem, in accordance with the present disclosure. Inputs related toobjects in an environment around the vehicle are monitored by a datafusion module. The data fusion module analyzes, filters, or prioritizesthe inputs relative to the reliability of the various inputs, and theprioritized or weighted inputs are summed to create track estimates forobjects in front of the vehicle. These object tracks are then input tothe collision threat assessment module, wherein each track is assessedfor a likelihood for collision. This likelihood for collision can beevaluated, for example, against a threshold likelihood for collision,and if a collision is determined to be likely, collisioncounter-measures can be initiated.

As shown in FIG. 16, a CPS continuously monitors the surroundingenvironment using its range sensors (e.g., radars and lidars) andcameras and takes appropriate counter-measurements in order to avoidincidents or situations to develop into a collision. A collision threatassessment generates output for the system actuator to respond.

As described in FIG. 16, a fusion module is useful to integrate inputfrom various sensing devices and generate a fused track of an object infront of the vehicle. The fused track created in FIG. 16 includes a dataestimate of relative location and trajectory of an object relative tothe vehicle. This data estimate, based upon radar and other rangefinding sensor inputs is useful, but includes the inaccuracies andimprecision of the sensor devices utilized to create the track. Asdescribed above, different sensor inputs can be utilized in unison toimprove accuracy of the estimates involved in the generated track. Inparticular, an application with invasive consequences such as automaticbraking and potential airbag deployment require high accuracy inpredicting an imminent collision, as false positives can have a highimpact of vehicle drivability, and missed indications can result ininoperative safety systems.

Vision systems provide an alternate source of sensor input for use invehicle control systems. Methods for analyzing visual information areknown in the art to include pattern recognition, corner detection,vertical edge detection, vertical object recognition, and other methods.However, it will be appreciated that high-resolution visualrepresentations of the field in front a vehicle refreshing at a highrate necessary to appreciate motion in real-time include a very largeamount of information to be analyzed. Real-time analysis of visualinformation can be prohibitive. A method is disclosed to fuse input froma vision system with a fused track created by methods such as theexemplary track fusion method described above to focus vision analysisupon a portion of the visual information most likely to pose a collisionthreat and utilized the focused analysis to alert to a likely imminentcollision event.

FIG. 17 schematically illustrates an exemplary image fusion module, inaccordance with the present disclosure. The fusion module of FIG. 17monitors as inputs range sensor data including object tracks and cameradata. The object track information is used to extract an image patch ora defined area of interest in the visual data corresponding to objecttrack information. Next, areas in the image patch are analyzed andfeatures or patterns in the data indicative of an object in the patchare extracted. The extracted features are then classified according toany number of classifiers. An exemplary classification can includeclassification as a fast moving object, such a vehicle in motion, a slowmoving object, such as a pedestrian, and a stationary object, such as astreet sign. Data including the classification is then analyzedaccording to data association in order to form a vision fused basedtrack. These tracks and associated data regarding the patch are thenstored for iterative comparison to new data and for prediction ofrelative motion to the vehicle suggesting a likely or imminent collisionevent. Additionally, a region or regions of interest, reflectingpreviously selected image patches, can be forwarded to the moduleperforming image patch extraction, in order to provide continuity in theanalysis of iterative vision data. In this way, range data or rangetrack information is overlaid onto the image plane to improve collisionevent prediction or likelihood analysis.

FIG. 19 illustrates exemplary range data overlaid onto a correspondingimage plane, useful in system-internal analyses of various targetobjects, in accordance with the present disclosure. The shaded bars arethe radar tracks overlaid in the image of a forward-looking camera. Theposition and image extraction module extracts the image patchesenclosing the range sensor tracks. The feature extraction modulecomputes the features of the image patches using following transforms:edge, histogram of gradient orientation (HOG), scale-invariant featuretransform (SIFT), Harris corner detectors, or the patches projected ontoa linear subspace. The classification module takes the extractedfeatures as input and feed to a classifier to determine whether an imagepatch encloses an object. The classification determines the label ofeach image patch. For example, in FIG. 19, the boxes A and B areidentified as vehicles while the unlabelled box is identified as aroad-side object. The prediction process module utilizes an object'shistorical information (i.e., position, image patch, and label ofprevious cycle) and predicts the current values. The data associationlinks the current measurements with the predicted objects, or determinesthe source of a measurement (i.e., position, image patch, and label) isfrom a specific object. In the end, the object tracker is activated togenerate updated position and save back to the object track files.

FIG. 18 schematically depicts an exemplary bank of Kalman filtersoperating to estimate position and velocity of a group objects,accordance with the present disclosure. Different filters are used fordifferent constant coasting targets, high longitudinal maneuver targets,and stationary targets. A Markov decision process (MDP) model is used toselect the filter with the most likelihood measurement based on theobservation and target's previous speed profile. This Multi-modelfiltering scheme reduces the tracking latency, which is important forCPS function.

Reaction to likely collision events can be scaled based upon increasedlikelihood. For example, gentle automatic braking can be used in theevent of a low threshold likelihood being determined, and more drasticmeasures can be taken in response to a high threshold likelihood beingdetermined.

Additionally, it will be noted that improved accuracy of judginglikelihood can be achieved through iterative training of the alertmodels. For example, if an alert is issued, a review option can be givento the driver, through a voice prompt, and on-screen inquiry, or anyother input method, requesting that the driver confirm whether theimminent collision alert was appropriate. A number of methods are knownin the art to adapt to correct alerts, false alerts, or missed alerts.For example, machine learning algorithms are known in the art and can beused to adaptively utilize programming, assigning weights and emphasisto alternative calculations depending upon the nature of feedback.Additionally, fuzzy logic can be utilized to condition inputs to asystem according to scalable factors based upon feedback. In this way,accuracy of the system can be improved over time and based upon theparticular driving habits of an operator.

It will be appreciated that similar methods employed by the CPS can beused in a collision avoidance system. Frequently such systems includewarnings to the operator, automatic brake activation, automatic lateralvehicle control, changes to a suspension control system, or otheractions meant to assist the vehicle in avoiding a perceived potentialcollision.

Additionally, numerous methods are known to achieve lane keeping orplace a vehicle within a lane by sensor inputs. For example, a methodcan analyze visual information including paint lines on a road surface,and utilize those markings to place the vehicle within a lane. Somemethods utilize tracks of other vehicles to synthesize or assist inestablishing lane geometry in relation to the vehicle. GPS devices,utilized in conjunction with 3D map databases, make possible estimatinga location of a vehicle according to global GPS coordinates andoverlaying that position with known road geometries.

An exemplary method for generating estimates of geometry of a lane oftravel for a vehicle on a road is disclosed. The method includesmonitoring data from a global positioning device, monitoring mapwaypoint data describing a projected route of travel based upon astarting point and a destination, monitoring camera data from a visionsubsystem, monitoring vehicle kinematics data including: a vehiclespeed, and a vehicle yaw rate, determining a lane geometry in an area ofthe vehicle based upon the map waypoint data and a map database,determining a vehicle position in relation to the lane geometry basedupon the lane geometry, the data from the global positioning device, andthe camera data, determining a road curvature at the vehicle positionbased upon the vehicle position, the camera data, and the vehiclekinematics data, determining the vehicle orientation and vehicle lateraloffset from a center of the lane of travel based upon the roadcurvature, the camera data and the vehicle kinematics, and utilizing thevehicle position, the road curvature, the vehicle orientation, and thevehicle lateral offset in a control scheme of the vehicle.

FIG. 20 depicts an exemplary vehicle utilizing a sensor to acquire roadgeometry data in front of the vehicle, in accordance with the presentdisclosure. The exemplary vehicle includes a passenger vehicle intendedfor use on highways, although it is understood that the disclosuredescribed herein is applicable on any vehicle or other system seeking tomonitor position and trajectory of remote vehicles or other objects. Thevehicle includes a control system containing various algorithms andcalibrations executed at various times. The control system is preferablya subset of an overall vehicle control architecture which providescoordinated vehicle system control. The control system monitors inputsfrom various sensors, synthesize pertinent information and inputs, andexecute algorithms to control various actuators to achieve controltargets, to effect for example collision avoidance and adaptive cruisecontrol. The vehicle control architecture includes a plurality ofdistributed processors and devices, including a system controllerproviding functionality such as antilock braking, traction control, andvehicle stability.

In the exemplary embodiment of FIG. 20, vehicle 760 includes a visionsubsystem 766. Vision subsystem 766 utilizes a camera or an imagingdevice capable of creating a digital image representation of the area infront of the vehicle. The data from vision subsystem 766 is utilized todescribe conditions in front of the vehicle and is translated into anXY-coordinate system 770 in reference to the central axis of vehicle760. An exemplary field of view for the vision subsystem is illustratedby the dotted lines. A lane of travel on the road is depicted accordingto lane markers 775A and 775B and describe common features that can bedetected visually and utilized to describe lane geometry relative tovehicle 760. In this way, by methods known to one having ordinary skillin the art, information gained from the analysis of image or camera datacan be utilized as conditions relative to the forward travel of vehicle760.

Each processor within the system is preferably a general-purpose digitalcomputer generally including a microprocessor or central processingunit, read only memory (ROM), random access memory (RAM), electricallyprogrammable read only memory (EPROM), high speed clock,analog-to-digital (A/D) and digital-to-analog (D/A) circuitry, andinput/output circuitry and devices (I/O) and appropriate signalconditioning and buffer circuitry. Each processor has a set of controlalgorithms, including resident program instructions and calibrationsstored in ROM and executed to provide respective functions.

Algorithms described herein are typically executed during preset loopcycles such that each algorithm is executed at least once each loopcycle. Algorithms stored in the non-volatile memory devices are executedby one of the central processing units and are operable to monitorinputs from the sensing devices and execute control and diagnosticroutines to control operation of a respective device, using presetcalibrations. Loop cycles are typically executed at regular intervals,for example each 3, 6.25, 15, 25 and 100 milliseconds during ongoingvehicle operation. Alternatively, algorithms may be executed in responseto occurrence of an event.

Sensors utilized by vehicle 760, such as a vision subsystem 766 or otherradar or ranging device, are preferably positioned within the vehicle760 in relatively unobstructed positions relative to a view in front ofthe vehicle. It is also appreciated that each of these sensors providesan estimate of actual details of the road or objects on the road infront of the vehicle. It will be appreciated that these estimates arenot exact locations, and standards of deviation for each estimate arepossible. It is further appreciated that the characteristics of thesesensors are complementary, in that some are more reliable in estimatingcertain parameters than others. Conventional sensors have differentoperating ranges and angular coverages, and are capable of estimatingdifferent parameters within their operating range. For example, radarsensors can usually estimate range, range rate and azimuth location ofan object, but are not normally robust in estimating the extent of adetected object. A camera with vision processor is more robust inestimating a shape and azimuth position of the object, but is lessefficient at estimating the range and range rate of the object. Scanningtype Lidars perform efficiently and accurately with respect toestimating range, and azimuth position, but typically cannot estimaterange rate, and are therefore not accurate with respect to new objectacquisition/recognition. Ultrasonic sensors are capable of estimatingrange but are generally incapable of estimating or computing range rateand azimuth position. Sensors describing kinematics of the vehicle suchas velocity and yaw rate are not exact, and in particular, may not berobust when tracking small changes in vehicle motion. Further, it isappreciated that the performance of each sensor technology is affectedby differing environmental conditions. Thus, conventional sensorspresent parametric variances, whose operative overlap createsopportunities for sensory fusion.

A preferred control module includes a controller, wherein an algorithmand associated calibration are stored and configured to receive theestimate data from available sensors to cluster data into usableestimations of conditions in front of the vehicle, and to fuse theclustered observations to determine required lane geometry and relativevehicle position estimates. It is understood that fusing data usingdifferent sensing systems and technologies yields robust results. Again,it is appreciated that any number of sensors can be used in thistechnique.

One method to create and maintain estimates of road and lane geometrywithin a system is given wherein historical measurements are utilized toevaluate or predict subsequent track data. Exemplary systems makeestimates based upon functions at time T to describe a system state attime T+1. Frequently, in order to support real-time estimation, aninformation array to present a Gaussian distribution is used to estimateeffects of unknown error. Such systems enable collection and fusion ofestimations of road conditions in front of the vehicle. However, it willbe appreciated that such systems utilizing historical data and Gaussiandistribution include inherent error based upon averaging and normaldistribution assumptions. For example, in a lane geometry estimationoperation, establishing an estimated safe lane of travel for the vehicleto traverse, a straight lane behind a vehicle has no actual lesseningimpact on a sharp turn in the road in front of the vehicle. Divergenceof data regarding the lane in front of the vehicle is not necessarilyimproved by application of a random vector with Gaussian distribution toresolve the divergence. Methods utilizing historical averaging andnormalized or Gaussian distributions, such as methods relying uponKalman filters, frequently include an error factor resulting in time lagto changes or transitions in road geometry.

An alternate method is disclosed to generate estimates of lane geometryand vehicle position and orientation in relation to the lane withoutincurring errors based upon historical data or normalized distributionsby fusing current measurements from GPS data, a vision camera subsystem,and vehicle kinematics.

General road geometry is information that has been made readilyavailable through the use of GPS devices and 3D maps. Given anapproximate location from the GPS device, localized road geometries canbe rendered into a list of road shape points. Similarly, GPS coordinatesincluding a global latitude measurement and a global longitudemeasurement are available through the GPS device. Vehicle kinematicsincluding at least vehicle speed and yaw rate are available throughsensors monitoring vehicle operation and/or monitoring accelerometerreadings. Camera data is available for localizing the vehicle to anactual lane of travel. Lane sensing coefficients are defined throughcamera data (i.e., y=a+bx+cx²+d³, where x is the lane longitudinaloffset, and y is the lateral offset from the lane center). Through thisdata, the forward lane estimation module may estimate the curvature ofthe lane, lateral offset from the lane center, and vehicle orientationwith respect to the tangent of the lane.

FIG. 21 illustrates an exemplary forward lane estimation process, inaccordance with the present disclosure. The exemplary process includes amap geometry model module, a vehicle pose localization module, acurvature estimation module, and a vehicle lateral tracking module. Themap geometry model module inputs map waypoints, determined by methodsknown in the art including determining generalized paths from a startingor present point to a destination or through point in a map database,and outputs a lane geometry in the area of the vehicle. This lanegeometry can be described as an arc including a geometric representationof the roads in the area. The vehicle pose localization module inputsthe lane geometry from the map geometry model module, GPS coordinatesfrom a GPS device, and camera data from a vision subsystem and outputsan estimated vehicle position in relation to the lane geometry in thearea of the vehicle. This vehicle position in relation to the lanegeometry or the arc can be described as an arc length parameter (s_(m)).The curvature estimation module inputs camera data, vehicle kinematicsdata, such as vehicle speed and yaw rate, from vehicle sensors, ands_(m) and outputs a curvature (K) or a measure of a curve in the road atthe location of the vehicle. Finally, the vehicle lateral trackingmodule inputs camera data, vehicle kinematics data, and K and outputsdata regarding the position of the vehicle with respect to the center ofthe current lane and the angular orientation of the vehicle with respectto the present forward direction of the lane. In this way, presentinputs relating to the current position and travel of the vehicle can beutilized to generate data related to the lane geometry in the area ofthe vehicle and the position and orientation of the vehicle in relationto the lane.

As described above, the map geometry model module inputs map waypointsand outputs a lane geometry in the area of the vehicle. In particular,the map geometry model monitors the input of map shape points asdescribed within a map database and constructs a geometric modelrepresenting the shape points. FIG. 22 depicts an exemplary processwherein information from a map database can be utilized to construct ageometric model of a road in an area of a vehicle, in accordance withthe present disclosure. The exemplary process includes collecting mapshape points describing road geometries from a map database. A mapdatabase supplies map shape points in global coordinates, frequentlydescribing positions in terms of a latitudinal position, a longitudinalposition, and a height or elevation. The global coordinates are thenconverted to a local coordinate system, usually identifying a pointproximate to the vehicle location as a static reference point anddescribing any other locations as a north displacement from thereference point and an east displacement from the reference point. Nextthe map shape points are fitted with a spline in order to generate ageometric shape or arc approximating the geometry of the roads beingrepresented. Finally, a tangent and a curvature of the fitted splinesare determined at an estimated position of the vehicle.

An exemplary determination within a map geometry model is described. Let{(lat_(i),lon_(i))|i=1, . . . , N} be the shape points. Picking a pointas the reference point, one can convert the shape points to localcoordinates {(e_(i),n_(i))|i=1, . . . , N}, representing the east andnorth displacements from the reference point. Defining the series{(s_(i),e_(i),n_(i))|i=1, . . . , N} with

${s_{1} = 0},{s_{i} = {\sum\limits_{k = 2}^{i}\sqrt{e_{k}^{2} + n_{k}^{2}}}},{i \geq 2},$we obtain a two-dimensional cubic spline function to fit the shapepoints as follows:

$\begin{matrix}{\begin{bmatrix}e \\n\end{bmatrix} = {f(s)}} & \lbrack 1\rbrack\end{matrix}$where s is the arc length parameter, e and n are the east and northcomponents of the displacements, respectively. Then the gradient vectorat s is computed as follows.

$\begin{matrix}{\begin{bmatrix}e^{\prime} \\n^{\prime}\end{bmatrix} = {f^{\prime}(s)}} & \lbrack 2\rbrack\end{matrix}$And the orientation angle is computed as follows.ξ=a tan 2(n′,e′)  [3]In the end, the curvature K at s can be computed as follows:

$\begin{matrix}{{\kappa = \frac{{e^{\prime}n^{''}} - {n^{\prime}e^{''}}}{\left( {e^{\prime 2} + n^{\prime 2}} \right)^{3/2}}}{{{where}\mspace{14mu}\begin{bmatrix}e^{''} \\n^{''}\end{bmatrix}} = {{f^{''}(s)}.}}} & \lbrack 4\rbrack\end{matrix}$As described above, the vehicle pose localization module inputs the lanegeometry from the map geometry model module, GPS coordinates from a GPSdevice, and camera and outputs an estimated vehicle position in relationto the lane geometry in the area of the vehicle. One having ordinaryskill in the art will appreciate that a problem can be described oflocalization in a map to monitored GPS data. Map geometry is representedby a spline function, such as the function described in Equation 1. Thisspline describes discreet locations wherein a lane of a road is the toexist. A point measured by GPS data is returned in an exemplary form

$P = {\begin{bmatrix}x \\y\end{bmatrix}.}$Inaccuracy and imprecision of some deviation is normal in GPS devices.Error is also inherent in the spline function. P is rarely preciselycoincident with the map geometry spline. The spline function describes apoint in the lane, for example the center of the lane, and the actualvehicle position will frequently deviate from the center of the lane bya measureable amount. An approximate location of the vehicle on a mapmust be determined based upon P and the estimated road geometry in thearea. One exemplary solution to correct deviation between P and thegeometric representation of the road is to find the closest point[e_(m),n_(m)]^(T)=f(s_(m)) such that

$s_{m} = {\underset{s}{argmin}{{{P - {f(s)}}}.}}$This exemplary process is useful to approximate s_(m) and may be appliediteratively to find the vehicle location in a road curve and improve theestimated location as monitored data changes.

FIG. 23 graphically illustrates an exemplary iterative method to find anapproximate location of a vehicle with respect to an estimated roadgeometry, in accordance with the present disclosure. Let S₀ be theinitial guess of S_(m). The correction of arc length parameter can bewritten as follows:

$\begin{matrix}{{\Delta\; s} = \frac{\left( {P - P_{m}} \right)^{T}P_{m}^{\prime}}{P_{m}^{\prime}}} & \lbrack 5\rbrack\end{matrix}$where P_(m)=f(s₀) and P′_(m)=f′(s₀). In other words, the correction Δsis the projection on unit vector of the gradient at the guess locationS₀.

As will be appreciated by one having ordinary skill in the art, GPSmeasurements are not updated frequently as compared to typical invehicle sensor readings. An exemplary refresh rate of 1 Hz for moston-vehicle GPS receivers is common Additionally, updates are not alwaysreceived and may be noisy in urban regions or other areas wherein viewof satellite signals is obscured. Filtering techniques can be utilizedto compensate for the slow rate of GPS signal updates.

An exemplary vehicle pose localization module utilizes a Kalman filter.The vehicle pose is modeled as a vector and consists of eastdisplacement (e), north displacement (n), orientation with respect tolane (φ), and the arc length (s). Due to inertia, the vehicle pose doesnot change abruptly. Therefore the following constant-turning model isassumed:e′=e+v cos(φ+ξ)ΔT+w ₁n′=n+v sin(φ+ξ)ΔT+w ₂φ′=φ+ωΔT−κΔT+w ₃s′=s+vΔT  [6]where v is the vehicle speed; ω is the vehicle yaw rate; ΔT is the deltatime from the previous cycle; ξ is the current orientation of the road(c.f., (2)); κ is the current curvature of the road based on map curve;w₁, w₂, and w₃ are process noise term representing un-modeleddisturbance.

FIG. 24 depicts an exemplary vehicle pose localization process, inaccordance with the present disclosure. The process is triggerediteratively whenever new data from GPS, vehicle kinematic sensors, orcamera devices is monitored. Exemplary cycle times for the differentdata sources include 1 second for the GPS data, 20 ms for kinematicsdata, and 50 ms for camera data. The delta time ΔT is computed from thedifference of timestamps between the current and previous cycles. Thenthe predicted vehicle pose is computed using Equation 5. When GPS datais available, the measurement updates for vehicle pose isstraightforward using the following GPS measurement equations:e _(gps) =e+k ₁  [7]n _(gps) =n+k ₂  [8]where (e_(gps), n_(gps)) is the GPS measured location of the vehicle; k₁and k₂ are the measurement noise. After update of vehicle pose using GPSmeasurement, we compute the correct arc length parameter (s) usingEquation 5. This step is important to obtain correct K and ξ values byremoving the accumulated error caused by dead reckoning processing inEquation 6.

When camera data is available, the following measurement equations canbe used by the Kalman filter:a=e+k ₃  [9]b=φ+k ₄  [10]where a and b are camera lane sensing parameters; d is the perpendiculardistance of the current vehicle position to the center of lanerepresented the map curve; and k₃ and k₄ are the un-modeled measurementnoise. Let P_(m) be the point on the map curve with the closest distanceto the current vehicle position expressed by P=(e,n). Let vector mdenote the normal of the map curve at P_(m). Then the perpendiculardistance d can be expressed as d=(P−P_(m))^(T) m, where the normal m iscomputed as

$m = {{\begin{bmatrix}0 & {- 1} \\1 & 0\end{bmatrix}\begin{bmatrix}e^{\prime} \\n^{\prime}\end{bmatrix}}.}$

As described above, the curvature estimation module inputs camera data,vehicle kinematics data, such as vehicle speed and yaw rate, fromvehicle sensors, and s_(m) and outputs a curvature (K) or a measure of acurve in the road at the location of the vehicle. Once the vehicle islocalized in the map curve represented by s, one can find thecorresponding map curvature κ_(map) by Equation 4.

One notices that there are three sources of information to estimate theroad curvature: map curvature (κ_(map)), camera curvature (κ_(cam)=2c),yaw rate based curvature

$\left( {\kappa_{yaw} = \frac{\omega}{v}} \right).$The following describes an exemplary process that can be used to fusethese three curvatures together. Let κ_(fus) denote the fused curvaturewith the variance σ_(fus) ². Let σ_(map) ², σ_(yaw) ², and σ_(cam) ²denote the variance of the map curvature, yaw rate base curvature, andcamera curvature, respectively. We have the following update equations.When map curvature estimate is available, then

$\begin{matrix}{{\kappa_{fus} = \frac{{\sigma_{map}^{2}\kappa_{fus}} + {\sigma_{fus}^{2}\kappa_{map}}}{\sigma_{map}^{2} + \sigma_{fus}^{2}}},{And}} & \lbrack 11\rbrack \\{\kappa_{fus} = {\frac{\sigma_{map}^{2}\sigma_{fus}^{2}}{\sigma_{map}^{2} + \sigma_{fus}^{2}}.}} & \lbrack 12\rbrack\end{matrix}$When yaw rate curvature estimate is available, then

$\begin{matrix}{{\kappa_{fus} = \frac{{\sigma_{yaw}^{2}\kappa_{fus}} + {\sigma_{fus}^{2}\kappa_{yaw}}}{\sigma_{yaw}^{2} + \sigma_{fus}^{2}}},{and}} & \lbrack 13\rbrack \\{\kappa_{fus} = {\frac{\sigma_{yaw}^{2}\sigma_{fus}^{2}}{\sigma_{yaw}^{2} + \sigma_{fus}^{2}}.}} & \lbrack 14\rbrack\end{matrix}$When map curvature estimate is available, then

$\begin{matrix}{{\kappa_{fus} = \frac{{\sigma_{cam}^{2}\kappa_{fus}} + {\sigma_{fus}^{2}\kappa_{cam}}}{\sigma_{cam}^{2} + \sigma_{fus}^{2}}},{and}} & \lbrack 15\rbrack \\{\kappa_{fus} = {\frac{\sigma_{cam}^{2}\sigma_{fus}^{2}}{\sigma_{cam}^{2} + \sigma_{fus}^{2}}.}} & \lbrack 16\rbrack\end{matrix}$In the above equations, σ_(map) ², σ_(yaw) ², and σ_(cam) ² representthe confidence of the curvature information from different sources: map,in-vehicle sensor, and camera, respectively. The higher the variance ofa information source, the less contribution of this source to the fusedcurvature. Some heuristic rules are employed to choose different weightsfor the three sources. For example, when yaw rate is high, we willchoose small σ_(yaw) ² to derive the fused curvature.

As described above, the vehicle lateral tracking module inputs cameradata, vehicle kinematics data, and K and outputs data regarding theposition of the vehicle with respect to the center of the current laneand the angular orientation of the vehicle with respect to the presentforward direction of the lane. FIG. 25 illustrates an exemplarydetermination made within the lateral model of the vehicle, inaccordance with the present disclosure. The vehicle lateral trackingmodule monitors the inputs of vehicle kinematics (wheel speed v and yawrate ω) and the inputs of lane sensing parameters. A Kalman filter canbe utilized to integrate the data from vehicle kinematics and the lanesensing device. As shown in FIG. 25, the lateral offset y_(L) is thedisplacement from the center of the lane. κ_(road) is the estimatedcurvature. κ_(yaw) is the curvature estimated by the instantaneousvehicle path, i.e.,

$\kappa_{yaw} = {\frac{\omega}{v}.}$The measurement equation of the Kalman filter is expressed as b=φ anda=y_(L). A gating logic is implemented if the innovation error is largerthan a threshold. In other words, if the difference between predictedand actual measurements is larger than a threshold, we ignore the actualmeasurement at the current time instant.

FIG. 22 described a method to generate a geometric model representingthe road on which the vehicle is to travel. However, it will beappreciated that other methods to achieve the same goal are possible.For example, one method disclosed includes assigning a series ofwaypoints in front of the vehicle forming a projected lane of travelbased upon map data and information regarding the projected destinationof the vehicle. FIG. 26 illustrates an exemplary use of waypoints alonga projected lane in front of the vehicle to estimate lane geometry, inaccordance with the present disclosure. Iterative creations of waypointsat successive time intervals, the waypoints spaced in short distanceincrements, can be used to reinforce the estimated lane geometry infront of the vehicle. As the vehicle passes waypoints, the waypoints canbe disregarded and only waypoints still in front of the vehicleutilized. In this way, a projection of waypoints in front of the vehiclealong an estimated path can be utilized to estimate lane geometrythrough which the vehicle is likely to travel.

Real-time and dependable information regarding lane geometry and vehicleposition and orientation in relation to the lane can be useful in anumber of applications or vehicle control schemes. For example, suchinformation can be used in applications assisting the operator in lanekeeping, headlight modulation, improved navigation aids, and drowsinessalarms. However, one having ordinary skill in the art will appreciatethat a great number of applications can utilize such information, andthe disclosure is not intended to be limited to the particularembodiments described herein.

The aforementioned methods describe the use of vision or camera systems.Analysis of such information can be performed by methods known in theart. Image recognition frequently includes programming to look forchanges in contrast or color in an image indicating vertical lines,edges, corners or other patterns indicative of an object. Additionally,numerous filtering and analysis techniques related to image recognitionare known in the art and will not be described in detail herein.

An exemplary system to utilize available data, such as is made availableby image recognition applied to vision images to define a clear path infront of the host vehicle for travel upon, is disclosed in co-pendingU.S. patent application Ser. No. 12/108,581, entitled VEHICLE CLEAR PATHDETECTION, and is herein incorporated by reference.

As described above, an exemplary EVS system requires input sources forinputs describing an operating environment for the vehicle. As describedin the exemplary methods above, a number of sensor devices are known inthe art, including but not limited to radar, lidar, ultrasonic devices,and vision systems. Additionally, it will be recognized that informationregarding the operating environment can be acquired from other types ofdevices. Infrared sensors or infrared range camera systems can beutilized to detect temperature differences. Such information can beuseful to seeing objects that would normally be obscured from normalvision or camera systems or the human eye. Methods are known to renderinfrared camera data into the visual spectrum, such that smalldifferences in temperature display objects in different colors to theviewer. As described above, a GPS device utilized in conjunction with a3D map database can be utilized to not only position the vehicle withrespect to a cataloged road geometry, but also to place the vehicle inthe context of road details, such as road surface type and road inclineor grade. Additionally, a number of sensors and monitoring methods areknown to quantify operating parameters within the vehicle. Additionally,remote processing made available through a wireless network allows forcoordination between the vehicle location set by GPS device andreal-time details, such as construction, weather, and traffic.

Additionally, non-road/non-traffic related details can be accessedsimilarly through the wireless network, for example, includinginternet-available data and infotainment services available throughon-line providers. On-board systems can further be integrated with theEVS, for example, maintenance requests logged by an on-board diagnosticmodule, for example, monitoring accumulated age upon engine oil ormonitoring tire pressures, can be utilized as inputs to the EVS. Thisinformation can be directly displayed based upon on-board processing;the information can be coordinated with on-line services, for example,diagnosing an issue with a selected service shop processor; or theinformation can be processed in accordance with a 3D map database, forexample, identifying a need to stop at a tire shop and locating severalnearby shops, including operating hours and customer reviews, based uponvehicle location. A wide variety of inputs are available for use by anEVS and the EVS system manager, and the disclosure is not intended to belimited to the exemplary inputs described herein.

All of the mentioned inputs can be utilized by an exemplary EVS systemmanager. Additionally, it will be appreciated that the EVS systemmanager has access to methods described above related to targettracking, CPS, collision avoidance, lane keeping, and clear pathdetection. These methods and related programming enable the EVS systemmanager to evaluate driving conditions, including tracks of objectsaround the vehicle, lane identification, and road conditions, andidentify information critical to the operation of the vehicle accordingto a set of critical criteria.

The EVS system manager monitors inputs and determines whetherdiscernable information related to the operating environment of thevehicle warrants displaying the information on the windscreen. A widevariety and great breadth of information can be made available to an EVSsystem manager. However, an operator of a vehicle has a primary duty towatch the road, and additional information is helpful insofar as theinformation is presented discreetly in a format that aids in focusingthe driver's attention on critical information and does not distract thedriver from the primary duty. An exemplary EVS system manager includesprogramming to monitor inputs from various sources; discern from theinputs critical information by applying critical criteria includingpreset thresholds, learned thresholds, and/or selectable thresholds tothe inputs, wherein the thresholds are set to minimize non-criticaldistractions upon the operator; and requests graphics for display basedupon the critical information.

Thresholds determining critical information from the inputs can be basedupon a number of bases. The HUD system manager has access to a number ofinput sources of information and includes various programmedapplications to create a contextual operational environment model todetermine whether gathered information is critical information. Forinstance, a collision avoidance system or collision preparation system,as described above, can be utilized to judge of a likelihood of impactbased upon returns from a radar sensing system. A relative trajectory ofa sensed object can be used to label the object as critical informationin order to avoid collision. However, context of the input describingthe sensed object can be important to defining a threshold for labelingthe input as critical information. FIGS. 27-29 illustrate an exemplaryapplication of contextual information to sensed object data in order todetermine whether the sensed data is critical information, in accordancewith the present disclosure. FIG. 27 depicts a vehicle including threesequential data points describing a target object in front of thevehicle, each subsequent data point being closer to the vehicle than thepreceding data point. Vehicle 500 is depicted, collecting informationregarding the target object as relative range from the vehicle at timesT₁, T₂, and T₃. Without context, such data points converging upon thevehicle suggest imminent collision of the vehicle with the targetobject. FIG. 28 depicts an exemplary situation in which correspondingdata points would correctly indicate critical information to anoperator. Vehicle 500 is depicted traveling within lane 510. Vehicle 520is also depicted, traveling in the same lane 510 but in the oppositedirection of vehicle 500. In this case, the target object is on acollision path with the host vehicle, and therefore collected datapoints indicating the closing range to the target object would becorrectly identified as critical information. Identifying the targetobject on the HUD, in this case, would not be an unwarranted distractionto the vehicle operator. FIG. 29 depicts an exemplary situation in whichcorresponding data points could incorrectly indicate criticalinformation to an operator. Vehicle 500 is depicted traveling withinlane 510. Signpost 530 is also depicted directly in front of vehicle500. Returned object tracking data to the vehicle would indicatesignpost 530 to be on a collision course with vehicle 500. However, inthis case, contextual information including the speed of the signpost inrelation to the speed of the vehicle, indicating a stationary signpost,and contextual information related to the curve in lane 510 can be usedto disqualify object tracking data from signpost 530 as below athreshold for critical information. In the above exemplarydeterminations, contextual information to the target tracking data canbe achieved by a number of methods, including but not limited tocorrelating relative motion of the target to the host vehicle's speed,GPS data including map data describing lane geometry for the vehicle'spresent location, lane geometry described by visual or camera data,and/or pattern recognition programming analyzing images of the trackedobject sufficient to discern between an on-coming vehicle and asignpost. By creating a contextual environmental model, based upondetermined spatial relationships in relation to the vehicle, for the HUDsystem manager to evaluate the input data points regarding a targettrack, a determination can be made regarding the critical nature of theinformation, for example, indexing a likelihood of collision. Such amodel can be based upon complex programming including factors describinga large number of inputs judging, for example, likely road slip on apatch of road in front of the vehicle, road grade, a vehicle driving inopposing traffic above the speed limit, and the audio in the hostvehicle being turned up to a potentially distracting volume. On theother hand, such a contextual environmental model can be as simple as acomparison of current speed of the vehicle to an identified speed limitor a comparison of a range to a target vehicle in front of the hostvehicle to a threshold minimum range.

The above examples are only exemplary of a multitude of contextualdeterminations that a HUD system manager can make with regard tocritical information. Known methods allow use of GPS data in combinationwith information from a 3D map database to identify a proposed route toan identified destination. Integrating such methods with use of a HUDallows projection of turn-by-turn directions upon the HUD, including animportant benefit of enabling registration of the directions upon theactual road features visible through the windscreen. Use of a contextualmodel, placing the vehicle in a location with respect to visiblefeatures, allows directions to be customized to the operation of thevehicle and surrounding conditions. Such registration upon the visibleroad features enables more precise instructions for the driver asopposed to verbal and/or LCD map displays.

Known systems utilizing GPS devices can utilize an entered destinationto give in-route directions to the operator. However, known GPS devicesinclude slow sample rates and imprecise GPS measurements. As a result,GPS devices cannot provide input to the operator based upon contextualvehicle operation with regard to a planned route. The HUD system managercan project directional arrows upon the road to illustrate the plannedroute, but the HUD system manager can additionally construct acontextual operational environment model of the planned travel route,synthesizing available information to identify as critical informationinput describing deviation from the planned route. Not only can the HUDsystem manager utilize various sources of information to increaseaccuracy of information presented, for example using visual or camerainformation to improve accuracy of a GPS location, but the informationcan additionally be given contextual importance regarding thesurroundings of the vehicle, for example, including object trackinginformation or 3D map data. In one example, if a planned route includesthe vehicle exiting an expressway at an upcoming exit on the right sideof the road, GPS data can be used to prompt the operator to take theexit. However, GPS data synthesized into a contextual model includingvisual information describing a lane of travel can be used to judge theGPS data and the corresponding planned route against a criticalinformation threshold. For example, if visual data places the vehicle ina left hand lane of a three-lane-road and utilizing the upcoming exitwill require two lane changes, the information indicating the upcomingexit can be identified as critical information warranting a graphicaldisplay or an increased urgency in a graphical display upon the HUD. Inthe same circumstances, upon monitoring visual information indicatingthe car to be in the right hand lane corresponding to the exit andvehicle information indicating that the vehicle's right turn blinker hasbeen activated, the information indicating the upcoming exit can bedetermined to be non-critical information not warranting graphicaldisplay or only minimal display upon the HUD. Additionally, objecttracking, weather, visibility, or other sources of information can beused to affect how and when to display navigational aids.

Additional examples of applying critical information thresholds toinformation are envisioned. Address information corresponding to aparticular location of a vehicle upon a road can be determined by GPSdata and application of a 3D map database. Visual data including imagerecognition programming can be used to outline a building or a range ofbuildings estimated to include the destination address. Historical datacan be monitored, and such a destination outline can be consideredcritical information if the vehicle has never traveled to thedestination before or if the destination is included among aparticularly dense arrangement of buildings. In the alternative, a voicecommand from the operator can be used to define the destination outlineas critical. In another alternative, operator head location and eyeorientation can be monitored according to methods described below, andthe destination outline can be considered critical information basedupon the operator's head and eye movement indicating searching for anaddress.

Another example of applying a critical information threshold can includeanalysis of current weather conditions. Under normal driving conditions,projection of lines upon the HUD indicating lane boundaries would likelybe considered unwarranted and a distraction. However, upon indicationthat weather conditions such as fog, snow, rain, sun glare, or otherfactors exist or combine to create conditions in which view of lanemarkers can be obstructed, lane boundaries can be determined to becritical information. Weather conditions can be discerned by a number ofmethods. On-line data in conjunction with GPS data can be used toestimate current weather conditions. Visual data can be analyzed todetermine whether lane markers are visually discernable or whetherprecipitation or fog unduly hampers viewing distance sufficiently towarrant projection of lane markings. Sun rise and sun set timing andlocation in the sky can be determined according to a calendar and GPSlocation. This information regarding the position of the sun can becorrelated to a directional orientation of the car to determine lanemarkings to be critical information based upon the car being pointedtoward the sun. In the alternative, sun position can be estimated basedupon visual information. In a similar example, if visual informationindicates that a vehicle in opposing traffic with high beams activatedis potentially causing a blinding situation, lane markers can beindicated as critical information to assist the operator of the hostvehicle to stay in the current lane. In these ways, estimated operatorvisibility can be used to determine appropriate lane marker projectionupon the HUD. In the alternative, lane markings can be determined to becritical information based upon estimated vehicle position with thelane, for example, with the lane markings becoming critical informationas the lane markings are approached or crossed by the host vehicle.Position within the lane further illustrates a condition in which adegree of importance can be indicated for the critical information, withincreased importance being indicated as the vehicle nears and thencrosses the lane markers. Increasing intensity of the graphical imagesprojected upon the HUD, flashing graphical images, and correspondingaudio signals to the operator can be utilized based upon increasingindicated importance of the critical information. Such a position withinthe lane criteria could be utilized as a drowsiness indicator, forexample, with a single deviation being treated as non-criticalinformation, but with repeated deviation from the center of the lanebecoming critical information or increased importance information, forexample, prompting coordinated textual information or audible warnings.Under certain conditions, an overlaid thermal or infrared camera imageof the road could be utilized or requested by the operator whereinvisual conditions inhibit the operator from seeing the proper lane oftravel, for example, caused by an inoperative headlight.

Another example of applying a critical information threshold can includeanalysis of pedestrian presence and pedestrian motion. For example,normal movement of a pedestrian on a sidewalk moving parallel to thedirection of vehicular traffic can be determined to be non-criticalinformation. However, movement of pedestrian traffic in anotherdirection, for example, perpendicular to vehicular traffic, can beutilized as a threshold to identify critical information. Within thisexample, another example of indicating increasing importance of thecritical information can be illustrated. If a pedestrian is walkingperpendicularly to vehicular traffic on a designated side-walk, then agraphic indicating slight or moderate importance can be indicated. Inthe event that pedestrian traffic extending from the side-walk to thelane of travel or within the lane of travel is detected, a graphicindicating severe or increased importance can be indicated. In anotherexample of identifying critical information with regard to pedestriantraffic, current traffic light patterns can be analyzed and used toidentify critical information. If the host vehicle is at a stop light,pedestrian traffic corresponding to visual images indicating a “walk”light indication can be determined to be non-critical information.However, in the same circumstances, pedestrian traffic corresponding toa “do not walk” light indication can be determined to be criticalinformation. In the alternative, visual information and rangeinformation to a target can be used to project an estimated size of thetarget. Such an estimated size could be used to identify, for example,all pedestrians estimated to be less than four feet tall to be criticalinformation so as to alert the driver to children in the operatingenvironment. In the alternative, a school zone or area with a deaf childcan be identified through street sign recognition application of GPSdata and a 3D map, local radio frequency transmission or tagging, etc.,and all pedestrians can be labeled as critical information in such azone. In situations wherein pedestrian traffic is detected butdetermined to not be visible, a graphic utilizing thermal or infraredimaging data can be selectively overlaid over the view of thepedestrian, in order to enable the vehicle operator to make a betterdecision regarding the situation.

Additional embodiments of critical information discernable by the EVSsystem manager are disclosed. In one exemplary use, recommendedfollowing distances between the host vehicle and other vehicles can becompared to measured ranges, and any range below the minimum recommendeddistances can be identified as critical information for display. Inanother example, wherein a vehicle is being utilized to train a newoperator, graphics displayed to the passenger/trainer can be used toimprove auditing of the new operator's actions. In another example, avehicle operating under semi-autonomous control or ACC can displaycritical information communicating current ranges to other vehicles orother information describing actions by the control system to theoperator such that the operator can quickly ascertain whether manualintervention by the operator is necessary. In another example, vehicleto vehicle communication can be utilized to simultaneously manage amerging maneuver between two vehicles utilizing ACC. Graphics upon theHUD can be used to communicate the intention to each of the drivers toperform a merging maneuver, in order to inform each driver of thecommunicated intent so as to avoid unexpected changes in vehicle motionand avoid a perception of imminent collision. In a similar application,in vehicles utilizing semi-autonomous driving, wherein automatic vehiclelateral control is utilized through a lane keeping system coupled withan automatic steering mechanism, graphics upon the HUD can be utilizedto inform the operator in advance that a lane change or other action isimminent, such that the operator is not surprised by the actionsubsequently taken by the semi-autonomous controls.

In another embodiment, vehicle to vehicle or vehicle to remote servercommunication can be utilized to monitor vehicle operation and identifypatterns in vehicle operation. For example, a slow-down due to anaccident can be monitored through the operation of numerous vehicles,and the information can be relayed to additional vehicles approachingthe area. The information can be termed critical information based uponmonitoring how much of a delay the slow-down has caused in the vehiclesalready affected and appropriately alerting of the delay andrecommending an alternate route. In another example, vehicle wheel slipcan be monitored in a number of vehicles, and vehicle approaching theparticular stretch of road causing the wheel slip can include agraphical patch projected upon the road surface indicating a probableslippery road condition. The information can be determined to becritical information based upon an occurrence of slip events on theparticular stretch of road or can be based upon a comparison ofoperation of the displaying vehicle versus operation of the vehicleexperiencing the slip. For example, three vehicles exceeding 50 milesper hour are determined to have slipped on this stretch of road in thelast hour, but the information is determined to not be critical basedupon the host vehicle traveling at 35 miles per hour. In anotherembodiment, wildlife can be monitored by the vision system, potentiallyaugmented by a radar system, and indicated as critical informationdepending upon a projected classification of the wildlife. Anidentification of a horse contained in a field can be determined to benon-critical information, whereas an identification of a white-taileddeer bounding toward the road can be determined to be criticalinformation.

Embodiments related to information regarding the surroundings of thevehicle are envisioned. For example, points of interest can be selectedas critical information for display on the HUD. A family touring anunfamiliar city can receive information regarding landmarks encounteredupon the route. Similarly directions to landmarks or a proposed touringroute can be selected and displayed through the EVS. A sports fan canselect a team or sport of interest, and upon traveling past a stadium orarena, access through wireless communication can be used to check gametimes, ticket cost, and current seat availability for automaticprojection upon the HUD. An antique collector can request notificationupon traveling within a certain distance of an antique store, an estatesale, or a flea market, and graphical directions to the location can bedisplayed upon request. An occupant searching for a new home can requestnotification and directions thereto if a new listing of a home for saleis posted meeting selected criteria in order to get the most recentlistings. An automotive enthusiast can request that a vehicle brand ormodel identified through visual recognition be identified by a graphicalimage. A number of applications to identify points of interest areenvisioned, and the disclosure is not intended to be limited to theparticular embodiments described herein.

Embodiments are envisioned for use by emergency personnel. For example,an ambulance equipped with the disclosed EVS system can communicate withvehicles or a remote server to include pertinent information on-route tothe scene of the emergency. For example, suggested routes can be updatedon-route by a dispatcher, a policeman on the scene can alert theapproaching ambulance of a dangerous situation, or a vehicle on-sitewith an identified serious injury can communicate with the ambulance inorder to implement a graphic to identify the vehicle with the injuryupon approach. Police vehicles can utilize graphics to communicatebetween police vehicles, for example, identifying a target vehicle underpursuit in one vehicle and creating a graphic in other police vehiclesjoining the pursuit. In another example, vehicles can utilizecommunications with a remote server to receive information regardingvehicles identified in association with a situation, for example, anAmber Alert. For example, license plates identified as wanted can berecognized through software known in the art combined with the visionsystem. This information, without the knowledge of the non-emergencyvehicle and thereby without endangering the occupants of the vehicle,can be communicated to emergency personnel and forwarded to the EVSsystem manager of the closest police vehicle for graphical display.Police vehicles can additionally utilize thermal imaging to search ascene for hidden or incapacitated persons across a landscape. Firevehicles can use the EVS system to enhance operation, for example, byassisting in evaluating the situation upon arrival. For example, if thedispatcher received a call from a person trapped in the third floor,northwest corner of a building, the dispatcher could enter the addressand the room information, and the particular room of the building couldbe identified as critical information requiring a graphic image by theEVS system. In another example, thermal imaging could be switched on ina vehicle stopped at the scene of a fire to assist the fire personnel indetermining the location and progression of the fire from a safelocation. A number of such applications are contemplated, and thedisclosure is not intended to be limited to the particular examplesdescribed herein.

A number of convenience applications are envisioned. For example, apixelated field of view limited architecture is disclosed enabling aviewer looking at the HUD from one direction seeing one image, andanother viewer looking at the HUD from another direction either notseeing the particular image or seeing a different image than the firstviewer. Such a system would allow a passenger to view images unrelatedto travel on the windscreen, while the vehicle operator continued toview only images related to operation of the vehicle. For example, apassenger could view infotainment type images such as internet content,video from a data storage device, or utilize an on-board camera to usethe display as a vanity mirror without disturbing the view of thedriver. Such content could be tied into other systems, with thepassenger checking restaurant menus from the internet along theprojected route of the vehicle and selecting a restaurant as an interimdestination in the projected route without distracting the vehicleoperator. Such a system could additionally enable an operator of avehicle to view images appropriately registered to the windscreenwithout the passenger seeing the same images, unregistered andpotentially annoying to the passenger.

One advantage of HUD applications is placing information in front of anoperator in a single field of vision with other critical informationsuch as a view through a windscreen. In known aerospace applications,HUD devices are utilized to allow a pilot to keep eyes upon the exteriorview while being presented with critical information such as air speedand altitude. Such a presentation of information in the same field ofview with visual information reduces the loss of concentration, thedistraction, and the momentary disorientation associated with movingone's eyes from an external view to a panel of instrumentation.Similarly, the EVS can present display information to a vehicle operatorin a single field of view with the external view visible through thewindscreen. Such information can be presented full time. However, toavoid distraction, the information can be filtered according to criticalinformation status or according to importance. For example, differentinformation is critical or important at low speed as compared to highspeed. Critical information to display upon the windshield can bemodulated based upon threshold vehicle speeds. Engine speed, when withinnormal ranges, may not be classified as critical information or onlydeserve a minimal, low intensity display. However, upon engine speedsincreasing to higher levels, the display can be activated or intensifiedto warn the operator of potential harm to the engine. Fuel level statusin the vehicle fuel tanks can similarly be not displayed or minimallydisplayed based upon a full or nearly full tank. Various levels ofincreased importance can be implemented, for example, with a displaydoubling in size as the fuel tank empties below a quarter tank, and witha flashing indicator as some critical low fuel level is passed. Levelsof critical information and levels of importance can be customized bythe vehicle operator, for example, through selectable menus on a vehicledisplay. Additionally, displays and levels of critical and importantinformation can be adjusted based upon operator preference through awireless network or by direct connection of a computer, for example,through a USB connection, with the vehicle. Such customization couldinclude an operator selecting display shapes, line weights, line colors,locations upon the windscreen, or other similar preferences. A displaytheme or skin can be selectably switched based upon vehicle speed orroad type, for example, an operator configuring a highway theme and aside-street theme. Themes could be selected according to GPS location,with a city theme and a countryside theme. Designs for customizeddisplays upon the windscreen could be shared upon user websites oracquired commercially from the vehicle manufacturer or other thirdparties. Displays can be coordinated with commercially availabledevices, for example, a digital music player, and integrated into adisplay theme, for example, with the display of the music playertransmitted in a corner of the HUD. A single vehicle, equipped withknown methods to determine an operator identity, could automaticallyload preferences for that operator. Many embodiments of displays thatcan be projected upon the windscreen are envisioned, and the disclosureis not intended to be limited to the particular embodiments describedherein.

Other displays can be projected upon the windscreen to minimize a needfor the operator to remove eyes from the windscreen. For example,adjustable cameras in the rear of the vehicle can be used to project asmall image of a sleeping infant in a car seat in a rear row of thevehicle, allowing the operator to monitor the child without turningaround to look. A more panoramic view could be implemented to monitormultiple children. Such a monitoring function could be in real-time orcould include a playback function.

As described above, a passenger can in certain circumstances viewinfotainment types of information. Clearly and as sometimes required byregulation, distractions to the vehicle operator must be minimized. Whena vehicle is in motion, information such as video content or e-mailcommunications would not be advisable to be visible to the operator.However such applications can be made available, where permitted, forexample, upon vehicle information indicating that the vehicle is in apark transmission state or if the vehicle's parking brake is engaged.Other applications may be possible presenting limited information to theoperator without introducing undue distraction, for example, includingsports scores from the internet, news headlines from the internet, orinformation on music currently being played in the vehicle, for example,giving a song title and artist name as a minimal graphic upon the HUD.

An exemplary embodiment of a pixelated field of view limitedarchitecture enabling image view from a limited direction includes useof micro-structures or an arrangement of particles accepting anexcitation light as described above and emitting light in a limiteddirection. FIGS. 30 and 31 schematically depict an exemplary use of apixelated field of view limited architecture, in accordance with thepresent disclosure. FIG. 30 depicts an exemplary emitter, capable ofemitting light to a limited field of view. The exemplary emitterincludes a UV transparent encapsulant, for example, made from SiO₂,filled with an LIF material that fluoresces visible wavelengths whenirradiated with ultraviolet radiation, with a parabola shaped narrowband multilayer reflection structure. In this exemplary embodiment, athin film of these emitters is deposited as onto a polymer. Inpreparation for the film, impressions in the shape of parabolas similarto the shape formed in the emitters are embossed into the polymermaterial. The emitters are deposited by chemical vapor deposition ontothe polymer substrate, filling the parabola impressions with emitters.FIG. 31 describes an exemplary process to create the necessary structureof emitters aligned to a polymer substrate in order to enable limitedfield of view viewing. By an exemplary process such as etching, freestanding parabolas that are filled with emitting material are created byreleasing them from the substrate. The removal from the polymersubstrate can be also be accomplished by dissolving the plasticsubstrate with a suitable solvent. The free standing parabolas are thennested into divots that have been created in the glass substrate byphotolithographic methods or embossing. The method of mating theparabola to the divot can be accomplished by a process such as fluidicself assembly, similar to that practiced by Alien Technology, whereinthe parabolas are flowed over the substrate and parabola-divot matingoccurs in a statistical fashion.

Head and eye sensing devices are known in the art and will not bediscussed in great detail here. For the purposes of this disclosure, acamera based device is utilized in combination with image recognitionsoftware to estimate a three-dimensional head location within thevehicle, able to be coordinated with a vehicle coordinate system, and adirection of an operator's gaze based upon image recognitionprogramming. Location of an object with relation to a vehicle coordinatesystem is ascertainable through sensor inputs, for example, according tothe tracking methods described above. Based upon operator head locationcoordinated with the vehicle coordinate system and upon object trackscoordinated with the vehicle coordinate system, an estimated point ofintersection between the tracked object and the operator's eyes can bedetermined upon the windscreen, thereby enabling registration ofinformation to relevant features visible through the windscreen, inaccordance with the disclosure. Similar methods are possible with lanemarker projection and other methods described herein, allowing accurateregistration of information to the HUD. Similarly, head locationcombined with estimation of the direction of the operator's gaze allowsfor projection of information according to methods intended to ensurethe operator sees critical information as soon as possible. Similarmethods could be implemented with the passenger in the front seat orpassengers in rear seats of the vehicles, allowing registered projectionfor vehicle occupants upon various surfaces.

Head and eye sensing devices enable the EVS to discern a direction ofthe operator's gaze. This gaze location can be compared to identifiedcritical information. A peripheral salient feature enhancement featureis disclosed, wherein display properties are modulated based uponattracting the operator's eyes to critical information when theoperator's gaze is elsewhere while not overly distracting the driverwhen the operator's gaze is close to the displayed critical information.For example, if a vehicle is backing out of a space to the left side ofthe visible field of view and is determined to be on a potentialcollision course with the host vehicle, and the operator's gaze isdetermined to be toward the right side of the visible field of view, abox can be placed around the offending vehicle, and a flashing arrow canbe placed at the point of the operator's gaze, prompting the operator'sattention to the box.

The included EVS is enabled to project registered images across anentire windscreen, registering images to viewable objects or areasthrough the transparent windscreen. However, vehicle sensors can processand identify information which pertains to conditions outside of theview of the windscreen. For example, radar devices and/or camera devicesviewing areas to the sides or rear of the vehicle can identify trafficlight information, vehicle trajectories, presence of emergency vehicles,or other pertinent information. The EVS manager, in evaluating theenvironmental model generated corresponding to a piece of criticalinformation, determines whether the critical information can bedisplayed upon the windscreen in a position registered to relevantfeatures visible through the windscreen corresponding to the criticalinformation. In the event that the evaluating determines that therelevant features, based upon occupant head and eye position, are notwithin the viewable area of the windscreen, a graphic can be registeredto the windscreen, for example, at an edge of the windscreen closest tothe source of the critical information or at some offset from theoccupant's gaze indicating a need to look in the direction of thecritical information. For example, if a target vehicle trajectory andspeed indicates that the vehicle is likely to run a red light to theleft or right of the host vehicle, the EVS can acutely prompt anemergency warning to the operator in order to avoid a broadsidecollision. Although an exemplary EVS with only projection upon the frontwindscreen cannot register a graphical representation upon a visibleobject not within the viewable area of the windscreen, the EVS canprompt the vehicle operator to look toward the identified criticalinformation. In the event critical information is identified behind thevehicle, a prompt can be displayed on the windscreen pointing to oroutlining the rearview mirror. In the alternative, a virtual rearviewmirror can be displayed upon the windscreen, utilizing a rearwardpointing camera. In the alternative, a panoramic view could be projectedusing multiple camera, for instance, in a broad, vertically thin patchof display along the top of the windscreen, illustrating, for example, aview around the rear 180 degrees of the vehicle, thereby eliminatingtraditional blind-spots caused by known mirror configurations. Inanother example, a HUD can be utilized in a rear window of a vehicle toprovide full screen parking assist by graphical images on the window.Such a rear window display can, for example, through voice recognitionsoftware, be selectably displayed in normal or reverse mode, enablingviewing directly or through the rearview mirror. In another example,based upon tracking information, a tactical or simulated overheaddisplay could be synthesized and projected upon the windscreen. Forexample, in a parking situation, radar and visual information could beused to estimate a relative location of a parking spot, other vehicles,curbsides, and pedestrian traffic, and these estimated locations can beplotted on a graphic display. Similarly, such a tactical display couldbe generated during lane change maneuvers, for instance, becomingcritical information once a blinker signal is turned on, and a displayshowing sensed objects around the vehicle could be displayed. Returningto a parking situation, such as a parallel parking maneuver, a set ofcriteria could be programmed, for example, monitoring no parking zonesand requiring a range of distances from the curbside and fromneighboring vehicles. Prompts or recommendations could be displayed uponthe windshield based upon spatial relationships, including highlightingavailable parking spots along city streets near a programmed destinationor recommended wheel and pedal controls to navigate into the parkingspot. Exemplary conditions and graphical displays are examples ofcritical information that can be displayed, prompting operator attentionto conditions outside of the view of the windscreen. However, theseexamples are intended to illustrate only a subset of the examplesenvisioned, and the disclosure is not intended to be limited thereto.

A number of enhancements to the EVS are envisioned, implementingfeatures especially relevant to automotive applications of suchprojection techniques. One having skill in the art will appreciate thatlaser and projector designs utilized to project complex imagesfrequently utilize a tiny or microelectromechanical systems (MEMS)mirror to direct the projected graphics to desired locations. Prior MEMSmirror laser projector designs have either a single stroke vector or abitmapped architecture, limiting efficiency and amount of informationpresented. An alternative method is disclosed, continuing to use thestroke implementation, but including multiple MEMS mirrors (MEMS chip)to direct a series of beamlettes. This disclosed method first implementsa Galilean telescope to beam expand the UV laser to a point whereseveral of the mirrors on a X direction MEMS multimirror device areirradiated. Each of the x mirrors (or group of x mirrors) is mapped andmated to a y mirror or group of y mirrors. The y mirrors are thenindependently aimed at the appropriate region of the emitting material.

Automotive applications include harsh conditions including potentialexposure to scratches, abrasion, and chemical contamination adverse tomaterials described above utilized in the HUD. Another embodiment ofsystem enhancements includes use of a protective coating over the lightemitting material on the HUD. However, and introduction of such a layerin the presence of the excitation light from the projection device andin the presence of the emitted light from the windscreen, as well as inthe presence of light passing through the windscreen from outside thevehicle, creates the potential for reflection and refraction issues,creating double images or ghosting. An ultraviolet anti-reflective (AR)coating can be applied to the inner surface of the windscreen tominimize ghosting. The AR coating can be either a single layer MgF₂ or amultilayer coating. A hard AR overcoat is needed to protect the emissivematerial used in a full windscreen HUD that has organicultraviolet-laser induced fluorescence material coating. Ghostingelimination requires a coating to couple the optical field effectively,avoiding a mismatch of the index of refraction of the material with theindex of refraction of air. Various materials can be added to improvethe AR coating and durability performance of the material. Multilayercoatings of a variety of materials and a variety of absolute andrelative thicknesses can be used to achieve the AR function. Convenientmaterials that can be deposited via magnetron sputtering or otherphysical and chemical vapor deposition methods include SiO2, Si3N4,TiO2, and SiOxNy. The last material, Siliconoxynitride has the advantageof having an index of refraction that is tunable via the O/N ratio(Stoichiometry).

Projecting an image upon a curved and slanted windscreen creates apotential for irregularities in the resulting graphic images. Oneexemplary issue to avoid includes luminance variance, or unintendeddifferences in graphic brightness caused by geometric differences in theexcitation light interacting with various portions of the HUD. Luminancecorrection is a compensation technique necessary for vector projectiondisplays. One method to achieve luminance correction includesre-parameterization of a parametric curve utilized in graphic renderingso that each segment of the path has the same effective scan length whenperforming sparse sampling. The efficient scan length can be evaluatedfrom the scanning unit area time rate which is a simulation of theillustration energy on the display screen. The perspective andnon-planar surface factors can be considered in the calculation of theeffective length.

Luminance variance is one potential irregularity that can makeprojection upon a windscreen difficult. Another potential irregularityincludes distortion in the graphical images created by geometricdistortions due to non-flat display surfaces, perspective, and opticalaberrations in large projection wide viewing angle systemconfigurations. A two pass distortion correction scheme is disclosed tocorrect geometric distortion of laser vector projection displays bymodeling the scan curves and projection screens withnon-uniform-rational b-spline (NURB) parametric curves/patches. In thefirst pass, the desired NURBs in object space will be transformed to theviewing space defined by a viewpoint. The perspective is then mapped toa virtual display plane due to their affine and perspective invariants.Finally it is mapped to the non-flat display surface with parametricspace mapping, if necessary. In the second pass, the path is transformedto a projection space that is defined by the position of the projector,and then the path is mapped to the projector plane. The non-lineardistortions are corrected by calibration methods.

Another potential irregularity that can be created in projectinggraphical images upon a windscreen includes inefficiencies created inthe scan loop utilized to project the graphical images. The scan loopconsists of the graphics primitive paths representing graphicsprimitives and the blanking paths that connect the primitive segments.Bad scan loop design will cause an inefficient display or displayfailure. The optimization on the paths will result in smooth andefficient scanning when mirror-based scanners are employed. Optimizingamong all the scan paths will obtain an efficient and smooth vector scanduring a scanning period or frame in a raster projection display.Invisible blanking paths can be optimized during insertion of the scanpath list to join the scan paths like a cursive script. Optimization canbe performed on the blanking paths so that all the blanking paths havethe first/secondary degree of continuity with their adjacent paths. Theparametric curve modeling will be employed. This method also utilizesthe optimization among all scan paths to obtain an efficient and smoothvector scan during a scanning period or frame in a raster projectiondisplay. Whole loop will be re-parameterized so that the loop has theshortest scan length and largest local radius of curvature.

A display will frequently require areas of zero intensity, for example,in projected images including a dotted line. A method is disclosed toimprove the image quality of vector projection engines that have lightsources that are directed with micromirrors. The method is applied tolaser projection devices that are directed at display screens usingmicromirrors (an x-scan and a y-scan mirror). The output is a lightvector whose position is stroked across the display screen, and theintensity of the light can be modulated via laser current. When zeroluminance is desired, a laser “off state” is desired. Unfortunately,response time to powering off and on a laser is slow relative to typicalscan speeds. Known methods create faint luminance lines where zeroluminance is desired. A method is disclosed to create zero luminance byutilizing an object in the path of the source light in order tocontrollably interrupt the excitation light projected upon the HUD. Forexample, objects inserted into the light path could include a knifeedge, a pin hole, or a mirror. Such mechanical blanking can beaccomplished on the order of the time scale of the scanning mirror sothere is response time matching.

A number of different utilities that can be accomplished throughselective projection of information upon a HUD by an EVS are disclosedabove. FIGS. 32-37 illustrate select exemplary displays of criticalinformation that might be projected upon a HUD, in accordance with thepresent disclosure. FIG. 32 depicts an exemplary un-enhanced externalview including features desirably visibly accessible to the operator ofthe vehicle. View 200 includes road surface 206, including a first lanemarker 202 and a second lane marker 204; a vehicle 208 also on theroadway; a pedestrian 210; a speed limit sign 214; and an upcoming curvein the road 216. All objects and features in view 200 are directlyviewable, and no graphical displays through an EVS are depicted.

FIG. 33 depicts an exemplary view obstructed by heavy fog and exemplaryenhanced vision displays that might be used to compensate for the effectof the fog. View 220 depicts the same view as depicted in FIG. 32,except that the view is obscured by fog. View 220 includes fog 221; afirst lane marker 202 and second lane marker 204, both directly viewablefor brief distances until obscured by fog 221; projected lane indicators222 and 224; vehicle indicator 228; pedestrian indicator 230; vehiclespeed display 234; and warning indicator 237. Projected lane indicators222 and 224 are projections of lane indicators not visible and are aidsto assist the operator in lane keeping despite the presence of fog 221.Projected lane indicators 222 and 224 include curved sections 236indicating an upcoming curve in the road corresponding to curve 216 inFIG. 32. It will be noted that lane indicators 222 and 224 areillustrated as distinct lines. Where numerous sensors are available torefine positional data and utilize, for instance, a 3D map or radarreturns from distinguishable features such as curbsides or guard rails,distinct lines may be use to convey with some certainty the position ofupcoming lane geometry. However, where fewer sources of information areavailable, vehicle position is not precisely set, or for some reasonother reason lane geometry is uncertain, ranges or bands of lines may beused to help guide the operator while conveying that extra care shouldbe taken to visually determine actual road geometry. Vehicle indicator228 illustrates to the operator a location and general behavior ofvehicle 208. Additionally, textual information including factors such asrange and an evaluation of relative movement can be displayed in orderto assist the operator in compensating correctly for the presence of thevehicle. Pedestrian indicator 230 gives the operator notice that apedestrian has been detected and the general position with respect tothe roadway. Different graphics or text may be used to describedifferent behaviors or characteristics of the pedestrian, in accordancewith methods described above. Sign 214, depicted in FIG. 32, is notvisible in FIG. 33 due to fog 221. However, speed limits for stretchesof road are knowable through other means, for example, through GPSdevices in accordance with 3D maps. Vehicle speed indicator 234 providesa listing of current vehicle speed and of the speed limit for the roadcurrently being traveled upon. As mentioned above, curve 216 is depictedin FIG. 32, and curved sections in the projected lane indicators 222 and224 give a location for the upcoming curve. In addition, a textualdisplay can describe the approach of the curve, including a distance tothe curve as described in FIG. 33. Additionally, a recommended change inspeed or some other indicator of the severity of the curve could beindicated either in text 237 or in combination with the graphics ofcurved sections 236.

FIG. 34 depicts an exemplary display of graphics improving safetythrough a lane change. View 240 includes first lane marker 202 andsecond lane marker 204, directly viewable through the windscreen;neighboring lane marker 242, also directly viewable; turn signalindicator 244; lane change tactical display 246; and textual displays248 and 249. Turn signal indicator 244 can include a simple arrow, aflashing arrow, a cycling graphic changing size, color, intensity,position, or other graphic depending upon the message being conveyed tothe operator. For example, in a lane change wherein no threat isdetected in the neighboring lane, a simple arrow may be discreetlydisplayed upon the HUD to convey that no threat is anticipated toforestall the maneuver. However, in the instance, as depicted in FIG.34, where a vehicle is positioned in the neighboring lane posing athreat of collision if a lane change is executed, the graphic may bechanged to indicate a message to stop the lane change, for example byflashing the indicator, changing the indicator to red, putting across-out/prohibited graphic over the indicator, or any other acceptabledisplay method to indicate alarm to the viewer. Tactical display 246 isdepicted illustrating a location of the vehicle and a relative track ofthe vehicle indicated as a threat. Lane marker projections may beindicated upon the tactical display to improve cognition of the relativepositions of the vehicles. FIG. 34 indicates arrows pointing to thevehicle posing the threat in order to draw more attention from theoperator to the situation. Further, text 248 attached to the tacticaldisplay and text 249 independently situated on the HUD are depicted,urging attention of the operator to the situation.

FIG. 35 depicts an exemplary situation wherein a peripheral salientfeature enhancement feature is utilized in combination with an estimatedoperator's gaze location to alert an operator to critical information.View 250 includes first lane marker 202 and second lane marker 204,directly viewable through the windscreen; distraction sign 254 andvehicle 208, both directly viewable through the windscreen; and a numberof graphics described below. An operator's gaze location 252 isdepicted, describing a point where the operator's eyes are apparentlyfocused, for example, as a result of focusing upon distraction sign 254.Location 252 is depicted for illustration of the example only and wouldnot likely be displayed upon the HUD as a result of the distraction sucha moving graphic would cause the operator. A track of vehicle 208indicates a movement that causes vehicle 208 to be classified as athreat. For example, vehicle 208 is depicted on a trajectory to crossthe lane marker 202 into the lane of the operator's vehicle. Indicatingthe identification of vehicle 208 as a threat, a vehicle indicator box256 is displayed around vehicle 208 including a directional arrowindicating a relevant piece of information, such as direction of travelof the vehicle. Additionally, text 259 is displayed describing thethreat condition. In order to bring the operator's attention from thearea of distraction sign 254 to the critical information of vehicle 208,a textual alert and accompanying arrow are displayed proximately to theoperator's gaze location. In this way, the operator's attention can bedrawn to the critical information as quickly as possible.

FIG. 36 depicts an exemplary view describing display of navigationaldirections upon a HUD. The view through the windscreen in FIG. 36includes a complex intersection 262 with five streets commonlyintersecting. View 260 includes intersection 262, directly visiblethrough the windscreen; buildings 266, directly visible through thewindscreen; traffic light 268, directly visible through the windscreen;and a number of graphics described below. Navigation arrow 264 isdepicted, registered to the specific street to be turned onto inintersection 262. Additionally, navigational data including a 3D map isutilized to identify a particular building 266 as a destination, and adestination indicator 267 including a box and text are depicted.Additionally, based upon vehicle information or the complexity of theintersection being presented to the operator, an indication throughwarning text 269 is displayed as critical information, conveying adetermination of a traffic signal ordering a stop, as a driving aid.

FIG. 37 depicts an additional exemplary view, describing criticalinformation that can be displayed upon a HUD. View 270 describes a viewof through a windscreen at night. View 270 includes headlightillumination 271, describing two cones of light visible through thewindscreen. Additionally, a virtual rearview mirror 272 is depicted,displaying a panoramic view around the sides and rear of the vehicle, ascollected through a camera or group of cameras. Exemplary view includesa vehicle 208. Represented views in the rearview mirror can be retainedas simple images or can include information such as range to a targetvehicle. Additionally, a wildlife indicator 274 is depicted, includingan overlaid section of infrared image, depicted in FIG. 37 as across-hatched square, in order to assist the operator to see thewildlife outside of the headlight illumination 271. Additionally,wildlife indicator 274 includes a directional arrow and warning textdescribing the situation to the operator. Additionally, text warning 276is depicted, describing detection of an audible siren, not yetcorrelated with visual information, indicating proximate location of anemergency vehicle. Additionally, sports score 278 is displayed textuallydescribing information of interest to the operator in a format designedto minimize distraction to the driver. Additionally, radio informationincluding the name of a currently played song and the group performingthe song is displayed, reducing the tendency of the operator to shiftgaze to instrumentation of the vehicle radio.

Embodiments are described above wherein graphics can be registered to anoccupant's gaze. It will be appreciated that displaying a graphicimmediately in the center of the viewer's gaze can be distracting.Instead, a graphic can be registered initially to some offset from thelocation of the viewer's gaze and fixed in that location. In this way,the viewer then has the graphic located conveniently close to thecurrent location of the viewer's gaze, but then can adjust to lookdirectly at the graphic as the viewer's priorities allow. The locationof the graphic can additionally take into account locations of trackedrelevant features. For example, a graphic can be located so as to avoida distracting conflict with a stop light, a pedestrian, or otherimportant features visible through the windscreen.

Information flows and processes to control the methods described abovecan take many embodiments. FIG. 38 schematically depicts an exemplaryinformation flow accomplishing methods described above, in accordancewith the present disclosure. Process 900 includes an EVS system manager110 monitoring information from various sources and generating displayrequirements, EVS graphics system 155 monitoring display requirementsfrom the EVS system manager 110 and generating graphics commands, and agraphics projection system 158 projecting light upon a head-up display150. A number of exemplary sources of information are described,including operator inputs, visual information through camera system 120,radar information from radar system 125, vehicle information fromexemplary vehicle speed sensor 130, GPS information from GPS device 140,3D map information from 3D map database 910, and internet content fromwireless communication system 145. It will be appreciated that thesesources of information can take many forms as described throughout thisdisclosure, and the disclosure is not intended to be limited to theparticular embodiments described herein. An occupant eye locationsensing system such as is described in FIG. 1 can be utilized; however,in this particular embodiment, other sources of information such asoperator inputs are utilized to estimate the location of the operator'shead and eyes for the purposes of image registration. It will beappreciated that GPS information, 3D map information, and internetcontent can be interdependent information. Correlation between thesesources of information can occur within EVS system manager 100, or, asdepicted in FIG. 38, the devices providing the information to the EVSsystem manager 110 can include programming to coordinate informationbefore or simultaneous to providing information to the system manager.Through this exemplary process, information can be monitored andutilized to project images upon a HUD.

The above embodiments describe image projection upon a windscreen of avehicle. However, the methods described herein can be applied to anyappropriate surface within the vehicle. For example, a projection systemcould be used solely upon the rear window of the vehicle. In anotherexample, a projection system could be used upon the side windows of thevehicle in any row, for example, in the second row of the vehicle. Sucha system, in cooperation with selectable or addable programming, couldbe used to entertain children on a trip, playing games such as promptingchildren to find various landmarks or letters upon objects outside ofthe vehicle. Information for the passengers could be displayed upon suchsurfaces, for example, time to destination, a digital map describingprogress of a trip, entertainment images, or internet content. Vehiclesemploying alternative windscreen configurations, for example, acircular, semicircular, dome shaped, or otherwise encapsulating canopydesign could similarly utilize the windscreen as a surface upon whichgraphical images can be displayed.

Information projected upon the HUD is described above to include thefull windscreen. However, the methods described herein need not beapplied to an entire windscreen. For example, in order to avoid makingthe operator look too far away from the straight ahead position, imagescould be limited to some conical area in the operator's view. In thealternative, images could be limited from being projected in front of apassenger so as to avoid annoying the passenger. In the alternative, azone in the center of the operator's view could be made free of images,thereby ensuring that no images distract the attention of the operatorfrom the most critical view of the path of the vehicle. In thealternative, a zone around the perimeter of the windscreen could beutilized to project images, retaining the entire middle of the screenfor exclusive view of the operator. In instances described above whereinthe entire view of the operator is not utilized, images can still beregistered to the windscreen, for example, with horizontal and verticaltick marks around the display free area indexing the location of theobject or condition being pointed to. Display configurations can beselectable by the operator or occupants or may be configured to displaydifferent schemes depending upon a number of criteria, for example, timeof day, number of occupants in the vehicle, location, or level ofimportance of the information, according to methods described hereinabove. Regions to include or exclude projection of display within thevehicle can take a number of different embodiments, and the disclosureis not intended to limited to the particular embodiments describedherein.

As discussed above, projecting an image upon a curved and slantedwindscreen creates a potential for irregularities in the resultinggraphic images displayed on the substantially transparent windscreenhead-up display. It is desirable to avoid irregularities relating toluminance variance, or unintended differences in graphic brightnesscaused by geometric differences in the excitation light interacting withvarious portions of the HUD. Luminance correction is a compensationtechnique that can be utilized in vector projection displays, whereinthe luminance intensity of a desired parametric curve modeling a shapeof a graphic to be displayed upon the substantially transparentwindscreen head-up display can be modified or re-parameterized toproject a projected parametric curve having luminance that issubstantially uniform. Additionally, the scan time or scan speed of thedesired parametric curve can be modified to project the projectedparametric curve. Alternatively, the desired parametric curve can bere-parameterized to project the projected parametric curve.

FIG. 39 schematically depicts a luminance correction system 901utilizing the graphics system 155 for generating graphics commands tothe graphics projection system 158 displaying a projected parametriccurve 912 upon a projection surface 914, in accordance with the presentdisclosure. With reference to FIGS. 38 and 39, the graphics system 155receives display requirements including a desired parametric curve 153from the EVS systems manager 110, wherein the EVS systems manager 110monitors information from various sources and generates the desiredparametric curve 153 therefrom. As will be discussed in greater detailherein, the shapes of graphical images to be displayed upon theprojection surface 914 utilizing vector projection are parameterizedwith non-uniform-rational b-spline (NURB) parametric curves to protectpotential irregularities in the resulting images such as distortion. Thedesired parametric curve 153 includes a plurality of control points anda plurality of graphic segments (hereinafter segments) based on thecontrol points. The segments contained in the desired parametric curve153 can often vary in luminance, wherein some segments have lessluminance (i.e., less bright) than others, and thus, non-uniformity interms of luminance can be presented in the desired parametric curve 153.

The graphics system 155 includes an intensity modulation driver 904 forreceiving and monitoring the desired parametric curve 153 from the EVSsystems manager 110. An intensity modulator 902 associated with theintensity modulation driver 904 is configured to modify the desiredparametric curve 153 by increasing the intensity of excitation light(e.g. ultraviolet light or infrared light) from light sources (e.g. aprojector or laser, depicted by device 20 shown in FIG. 2) in segmentsin the desired parametric curve 153 that are less bright than othersegments, and thereby establish luminance uniformity in the parametriccurve 912 to be projected. Likewise, the intensity of excitation lightfrom the light sources can be decreased in segments in the desiredparametric curve 153 that are more bright than other segments. In theexemplary embodiment, the excitation light is an ultraviolet (UV) laserbeam 903 containing the graphical commands to the graphics projectionsystem 158. Hence, the intensity modulator 902 associated with theintensity modulation driver 904 compensates for unintended differencesin graphic brightness in vector projection displays when it is indicatedthere is a luminance variance between the plurality of graphic segments

In the exemplary embodiment, the graphical commands contained in the UVlaser beam 903 are input to the graphics projection system 158. Thegraphics projection system 158 includes a phase modulator 906 and aprojection lens 910. The phase modulator 906 can include a 2-Dacousto-optical scanner (see. FIG. 11, device 615) or amicro-electro-mechanical system (MEMS) mirror device. In the exemplaryembodiment the UV laser beam 903 can be expanded and scanned by thephase modulator 906 to direct a plurality of laser beamlettes 908.Utilizing the phase modulator 906, it will be appreciated that theluminance correction system 901 can command uniform luminance among theplurality of graphic segments by decreasing the scan speed in graphicsegments that contain less luminance than other graphic segments, andthereby establish luminance uniformity in the parametric curve 912 to beprojected. Likewise, the scan speed can be increased in graphic segmentsthat contain more luminance than other graphic segments. Alternatively,the phase modulator 906 can be utilized to increase the scan time ingraphic segments that contain less luminance than other graphic segmentsand decrease the scan time in graphic segments that contain moreluminance than other graphic segments, to thereby establish luminanceuniformity in the parametric curve 912 to be projected. The laserbeamlettes 908 are thereby input into the projection lens 910, wherein aprojected parametric curve 912 having substantially uniform luminance isprojected upon a projection surface 914. A viewer 916 can view theprojected parametric curve 912 upon the projection surface 914, whereinthe projection surface 914 can be the substantially transparentwindscreen head-up display.

Exemplary embodiments include determining a luminance indicator for eachgraphic segment contained in the desired parametric curve 135. It isappreciated that the luminance indicator can determine luminancevariance in each segment based on an effective scan length of eachsegment and/or the radius of curvature of each segment in the desiredparametric curve. Thus, the luminance indicator can be based upon adirectly proportional relationship between the amount of luminance ineach of the graphic segments and the effective scan length and/or theradius of curvature of each of the segments. For example, graphicsegments having longer effective scan lengths have less luminance thangraphic segments having shorter effective scan lengths and graphicsegments having larger radius of curvatures have less luminance thangraphic segments having smaller radius of curvatures. Hence, tocompensate for luminance non-uniformity between graphic segments,graphic segments having shorter effective scan lengths require decreasedluminance, graphic segments having longer effective scan lengths requireincreased luminance, graphic segments having larger radius of curvaturesrequire increased luminance and graphic segments having smaller radiusof curvatures require decreased luminance. Utilizing the luminanceindicator, the luminance correction system 901 can command uniformluminance among the plurality of segments contained in the parametriccurve 912 to be projected.

In an example, if the luminance indicator is based upon determining theeffective scan length of each of the graphic segments, the luminancecorrection system 901 can command the intensity modulation driver 904 toincrease the luminance intensity for graphic segments having longereffective scan lengths and decrease the luminance intensity for graphicsegments having shorter effective scan lengths. Similarly, if theluminance indicator is based upon determining the radius of curvaturesof each of the graphic segments, the luminance correction system cancommand the intensity modulation driver 904 to increase the luminanceintensity for graphic segments having larger radius of curvatures anddecrease the luminance intensity for graphic segments having shorterradius of curvatures.

In another example, if the luminance indicator is based upon determiningthe effective scan length of each of the graphic segments, the luminancecorrection system 901 can command the phase modulator 906 to increasethe scan time for graphic segments having longer effective scan lengthsand decrease the scan time for graphic segments having shorter effectivescan lengths. Similarly, if the luminance indicator is based upondetermining the radius of curvatures of each of the graphic segments,the luminance correction system 901 can command the phase modulator 906to increase the scan time for graphic segments having larger radius ofcurvatures and decrease the scan time for graphic segments havingsmaller radius of curvatures.

In yet another example, if the luminance indicator is based upondetermining the effective scan length of each of the graphic segments,the luminance correction system 901 can command the phase modulator 906to decrease the scan speed for graphic segments having longer effectivescan lengths and increase the scan speed for graphic segments havingshorter effective scan lengths. Similarly, if the luminance indicator isbased upon determining the radius of curvatures of each of the graphicsegments, the luminance correction system 901 can command the phasemodulator 906 to decrease the scan speed for graphic segments havinglarger radius of curvatures and increase the scan speed for graphicsegments having smaller radius of curvatures.

Referring to FIG. 40, the desired parametric curve 153 discussed in FIG.39 is discussed in further detail. The desired parametric curve 153includes a plurality of control points 802 and a plurality of segments804 based on the plurality of control points 802. It is appreciated thateach segment 804 includes an effective scan length substantially equalto the distance between each adjacent pair of control points 802. Theplurality of control points 802 define the desired parametric curve 153,however, the plurality of segments 804 do not necessarily pass directlythrough the plurality of control points 802. Referring to portion 808, aplurality of control points 802 d-g are shown. Referring to portion 806,a greater distribution of control points 802 in a smaller area isevident compared to portion 808. As evidenced by portions 806 and 808,the distance between each control point 802 decreases as the radius ofcurvature of the desired parametric curve 153 decreases. For instance,the distance between each of the control points 802 in portion 806 isless than the distance between the control points 802 d-g in portion 808because the radius of curvature of the desired parametric curve 153 inportion 808 is larger than the radius of curvature of the desiredparametric curve 153 in portion 806.

As discussed above, each of the segments 804 has an effective scanlength. For example, the effective scan length between control points802 a and 802 b is shorter than the effective scan length betweencontrol points 802 b and 802 c. Furthermore, the distribution of controlpoints corresponds to the radius of curvature. For example, thedistribution of control points 802 is greater in portion 806 than thedistribution of control points 802 d-g in portion 808 due to the radiusof curvature being smaller in portion 806 than the radius of curvaturein portion 808. Subsequently, the effective scan length of each segment804 in portion 806 is smaller than the effective scan length of eachsegment 804 in portion 808. It is appreciated that the total amount ofphotonic energy imparted across each of the segments 804 is equal,regardless of the variances in effective scan lengths. It is furtherappreciated that the luminance intensity, scan time and scan speed inone segment 804 is substantially equal to the luminance intensity, scantime and scan speed, respectively, of each of the other segments 804.For instance, the luminance intensity applied to the segment 804 betweencontrol points 802 a and 802 b is equal to the luminance intensityapplied to the segment 804 between control points 802 b and 802 c; thetime elapsed to scan (i.e., scan time) the segment 804 between controlpoints 802 a and 802 b is equal to the time elapsed to scan the segment804 between control points 802 b and 802 c; and the scan speed to scanthe segment 804 between control points 802 a and 802 b is equal to thescan speed to scan the segment 804 between control points 802 b and 802c.

However, segments 804 having longer effective scan lengths have lessluminance than segments 804 having shorter effective scan lengths.Likewise, segments 804 having shorter effective scan lengths have moreluminance (i.e., brighter) than segments 804 having longer effectivescan lengths. For example, the segment 804 between control points 802 aand 802 b has more luminance than the segment 804 between control points802 b and 802 c. This contrast in luminance between segments 804 havingdifferent effective scan lengths results in non-uniformity in terms ofluminance presented in the desired parametric curve 153. For instance,portion 808 would have less luminance than portion 806 due to a smallerradius of curvature, and thus, greater spacing between adjacent controlpoints 802 d-g resulting in longer effective scan lengths in segments804 in portion 808. Determining a luminance indicator for each of thesegments and utilizing the luminance indicator to command uniformluminance among the plurality of graphic segments 804 can correctnon-uniformity in terms of luminance and thereby project a projectedparametric curve that is substantially uniform in terms of luminance.

Referring to FIGS. 39 and 40, the desired parametric curve 153 is inputinto the graphics system 155 of the luminance correction system 901. Innon-limiting examples, for simplicity, the exemplary method is appliedto the segment 804 between control points 802 a and 802 b and thesegment 804 between control points 802 b and 802 c. However, the methoddescribed in these non-limiting examples can apply to all the segments804 and respective control points 802 of the desired parametric curve153.

A luminance indicator is determined for the segment 804 between controlpoints 802 a and 802 b and a luminance indicator is determined for thesegment 804 between control points 802 b and 802 c. The luminanceindicator for each of the segments is based on the effective scanlengths for each of the segments, wherein the effective scan length forsegment 804 between control points 802 a and 802 b is shorter than theeffective scan length for the segment between control points 802 b and802 c. Therefore, the segment between control points 802 a and 802 b hasmore luminance than the segment 804 between control points 802 b and 802c. Utilizing the determined luminance indicator corresponding to theeffective scan length of each of the segments 804, the luminanceintensity can be increased for the segment 804 between control points802 b and 802 c and/or the luminance intensity can be decreased for thesegment 804 between control points 802 a and 802 b to command uniformluminance among the plurality of graphic segments in the desiredparametric curve 153. In an alternate example, the luminance intensityfor each segment can be determined by the radius of curvature of thescanned path.

It is appreciated that the excitation light source is a pure electronicdevice, wherein intensity is easier to control than the scan speed andor scanning time of the desired parametric curve due to the scanningbeing performed at harmonic frequency. However, it is furtherappreciated that controlling laser intensity is difficult for excitationlight sources exerting green lasers. Thus, when the excitation lightsource exerts green lasers it may be desirable to control the time toscan each segment 804 (i.e., scan time) or control the scan speed ofeach segment 804 to command uniform luminance

In another non-limiting example, and utilizing the determined luminanceindicator corresponding to the effective scan length of each of thesegments 804, the time elapsed to scan (i.e., scan time) segment 804between control points 802 a and 802 b can be decreased and/or the timeelapsed to scan segment 804 between control points 802 b and 802 c canbe increased to command uniform luminance among the plurality of graphicsegments in the desired parametric curve 153. In an alternative example,the scan time for each segment can also be determined by the radius ofcurvature of the scanned path.

In yet another non-limiting example, and utilizing the determinedluminance indicator corresponding to the effective scan length of eachof the segments 804, the scan speed to scan the segment 804 betweencontrol points 802 a and 802 b can be increased and/or the scan speed toscan the segment 804 between control points 802 b and 802 c can bedecreased to command uniform luminance among the plurality of graphicsegments 804 in the desired parametric curve 153. In an alternativeexample, the scanning for each segment can also be determined by theradius of curvature of the scanned path. It is further appreciated thatscanning the desired parametric curve 153 is performed at harmonicfrequency.

It should be appreciated that when the intensity modulator 902 increasesthe luminance intensity to increase the luminance in a segment 804, thephotonic energy imparted across the segment 804 is also increased whenprojecting the projected parametric curve 912 upon the surface 914.Likewise, when the intensity modulator 902 decreases the luminanceintensity to decrease the luminance in a segment 804, the photonicenergy imparted across each segment is also decreased when projectingthe projected parametric curve 912 upon the surface 914. It is furtherappreciated that when the phase modulator 906 increases the scan time toincrease the luminance in a segment 804, the photonic energy impartedacross the segment 804 is also increased when projecting the projectedparametric curve 912 upon the surface 914. Likewise, when the phasemodulator 906 decreases the scan time to decrease the luminance in asegment 804, the photonic energy imparted across the segment 804 is alsodecreased when projecting the projected parametric curve 912 upon thesurface 914. It is further appreciated that when the phase modulator 906decreases the scan speed to increase the luminance in a segment 804, thephotonic energy imparted across the segment 804 is also increased whenprojecting the projected parametric curve 912 upon the surface 914.Likewise, when the phase modulator 906 increases the scan speed todecrease the luminance in a segment 804, the photonic energy impartedacross the segment 804 is also decreased when projecting the projectedparametric curve 912 upon the surface 914.

In another non-limiting example, it is appreciated that portion 808including control points 802 d-g has less luminance than portion 806because the radius of curvature of the plurality of segments 804contained in portion 808 is greater than the radius of curvature of theplurality of segments 806 contained in portion 806. Thus, each segment804 between each of the control points 802 d-g is longer than theeffective scan lengths of the segments 804 between each of the controlpoints 802 in portion 806 due to larger radius of curvature in portion808. The exemplary method as described with reference to the segment 804between control points 802 a and 802 b and the segment 804 betweencontrol points 802 b and 802 c in the above examples, can be applied tothe plurality of segments 804 contained in portions 808 and 808,respectively, to command uniform luminance among the plurality ofsegments 804 in the desired parametric curve 153.

Furthermore, a reduced luminance intensity command can be utilized foreach of the control points 802. The reduced luminance intensity commandcan be zero luminance intensity to substantially eliminate each of thecontrol points on the projected parametric curve 912 on the surface 914from the viewer.

Referring to FIGS. 39 and 41, FIG. 41 depicts an alternative embodimentwherein the desired parametric curve 153 is re-parameterized to commanduniform luminance among a plurality of new graphic segments 840 forprojecting the projected parametric curve 912 upon the surface 914. Are-parameterized parametric curve 853 includes arranging a plurality ofnew equidistantly spaced control points 820 and arranging the pluralityof new graphic segments 840 based on the new equidistantly spacedcontrol points 820. It is appreciated that because the new controlpoints 820 are equidistantly spaced from one another, the effective scanlength of each of the new graphic segments 840 is substantially equal.Because the effective scan length of each of the new graphic segments840 is substantially equal, the luminance among the plurality of newgraphic segments 840 is substantially uniform without utilizing methodsof increasing or decreasing the luminance intensity, scan time and/orscan speed of the new graphic segments 840 to generate uniformluminance. It is appreciated that the plurality of new equidistantlyspaced control points 820 define the re-parameterized curve, however,the plurality of new graphic segments 840 do not necessarily passdirectly through the plurality of new equidistantly spaced controlpoints 820. It is further appreciated that the desired parametric curve153 is re-parameterized in the graphics system 155.

Furthermore, a reduced luminance intensity command can be utilized foreach of the new equidistantly spaced control points 820. The reducedluminance intensity command can be zero luminance intensity tosubstantially eliminate each of the new equidistantly spaced controlpoints 820 on the projected parametric curve 912 on the surface 914 fromthe viewer.

The above disclosure describes a substantially transparent head-updisplay capable of full-screen display. It will be appreciated thatsimilar methods can be employed upon windscreens utilizing asubstantially full-windscreen display, a partial windscreen display, forexample limited to the driver's half of the windscreen, or a displayfocused or limited to the straight-forward typical center of view of theoperator. Many embodiments of displays are envisioned, and thedisclosure is not intended to be limited to the particular exemplaryembodiments described herein.

The disclosure has described certain preferred embodiments andmodifications thereto. Further modifications and alterations may occurto others upon reading and understanding the specification. Therefore,it is intended that the disclosure not be limited to the particularembodiment(s) disclosed as the best mode contemplated for carrying outthis disclosure, but that the disclosure will include all embodimentsfalling within the scope of the appended claims.

The invention claimed is:
 1. A method to display a projected parametriccurve upon a transparent windscreen head-up display, the methodcomprising: monitoring a desired parametric curve to be projected uponthe transparent windscreen, the desired parametric curve comprising aplurality of control points and a plurality of graphic segments basedupon the control points, wherein each graphic segment is betweenadjacent pairs of the control points and comprising an equal magnitudeof luminance intensity to be output from a light source regardless of adistance between adjacent pairs of the control points; for each graphicsegment: monitoring at least one of a respective effective scan lengthand a respective radius of curvature, the respective effective scanlength equal to the distance between a respective adjacent pair ofcontrol points, and determining a respective luminance indicatorindicative of a magnitude of luminance directly proportional to at leastone of the monitored respective effective scan length and the monitoredrespective radius of curvature; when a variance is determined betweenthe respective luminance indicators for at least two of the graphicsegments comprising the equal magnitude of luminance intensity to beoutput from the light source, modifying the desired parametric curve tobe projected based on utilizing each of the respective luminanceindicators to command uniform luminance among the plurality of graphicsegments; and projecting the projected parametric curve upon thetransparent windscreen based on the modified desired parametric curve.2. The method of claim 1, wherein the plurality of graphic segments isnot required to pass through the control points.
 3. The method of claim1, wherein modifying the desired parametric curve to be projected basedon utilizing each of the respective luminance indicators to commanduniform luminance among the plurality of graphic segments comprises:increasing the magnitude of luminance intensity output from the lightsource for graphic segments to be projected having longer effective scanlengths; decreasing the magnitude of luminance intensity output from thelight source for graphic segments to be projected having shortereffective scan lengths.
 4. The method of claim 1, wherein modifying thedesired parametric curve to be projected based on utilizing each of therespective luminance indicators to command uniform luminance among theplurality of graphic segments comprises: increasing the magnitude ofluminance intensity output from the light source for graphic segments tobe projected having larger radius of curvatures; and decreasing themagnitude of luminance intensity output from the light source forgraphic segments to be projected having shorter radius of curvatures. 5.The method of claim 1, wherein modifying the desired parametric curve tobe projected based on utilizing each of the respective luminanceindicators to command uniform luminance among the plurality of graphicsegments comprises: maintaining the equal magnitude of luminanceintensity in each of the graphic segments to be output from the lightsource; increasing a scan time for graphic segments having longereffective scan lengths; and decreasing the scan time for graphicsegments having shorter effective scan lengths.
 6. The method of claim1, wherein modifying the desired parametric curve to be projected basedon utilizing each of the respective luminance indicators to commanduniform luminance among the plurality of graphic segments comprises:maintaining the equal magnitude of luminance intensity in each of thegraphic segments to be output from the light source; increasing a scantime for graphic segments having larger radius of curvatures; anddecreasing the scan time for graphic segments having shorter radius ofcurvatures.
 7. The method of claim 1, wherein modifying the desiredparametric curve to be projected based on utilizing each of therespective luminance indicators to command uniform luminance among theplurality of graphic segments comprises: maintaining the equal magnitudeof luminance intensity in each of the graphic segments to be output fromthe light source; decreasing a scan speed for graphic segments havinglonger effective scan lengths; and increasing the scan speed for graphicsegments having shorter effective scan lengths.
 8. The method of claim1, wherein modifying the desired parametric curve to be projected basedon utilizing each of the respective luminance indicators to commanduniform luminance among the plurality of graphic segments comprises:maintaining the equal magnitude of luminance intensity in each of thegraphic segments to be output from the light source; decreasing a scanspeed for graphic segments having larger radius of curvatures; andincreasing the scan speed for graphic segments having shorter radius ofcurvatures.
 9. The method of claim 1, wherein utilizing the luminanceindicator to command uniform luminance among the plurality of graphicsegments comprises: arranging a plurality of new equidistantly spacedcontrol points; and arranging a plurality of new graphic segments basedon the plurality of new equidistantly spaced control points; whereineach of the plurality of new graphic segments comprises a uniformeffective scan length; wherein the luminance indicator is directlyproportional to effective scan length.
 10. The method of claim 1,further comprising utilizing a reduced luminance intensity command foreach of the plurality of control points.
 11. The method of claim 1,further comprising utilizing a zero luminance intensity command for eachof the plurality of control points.
 12. The method of claim 9, furthercomprising utilizing a reduced luminance intensity command for each ofthe plurality of new equidistantly spaced control points.
 13. The methodof claim 9, further comprising utilizing a zero luminance intensitycommand for each of the plurality of new equidistantly spaced controlpoints.
 14. A method to display a projected parametric curve upon atransparent windscreen head-up display, the method comprising:monitoring a desired parametric curve to be projected, the desiredparametric curve comprising a plurality of non-equidistantly spacedcontrol points and a plurality of graphic segments between adjacentpairs of said control points, each of the plurality of graphic segmentscomprising an equal scan speed, an equal scan time and an equalmagnitude of luminance intensity to be output from a light source; foreach graphic segment: monitoring at least one of a respective effectivescan length and a respective radius of curvature, the respectiveeffective scan length equal to a distance between a respective adjacentpair of control points, and determining respective luminance indicatorindicative of a magnitude of luminance directly proportional to at leastone of the monitored respective effective scan length and the monitoredrespective radius of curvature; when a variance is determined betweenthe respective luminance indicators for at least two of the graphicsegments comprising the equal magnitude of luminance intensity to beoutput from the light source, modifying the desired parametric curve tobe projected based on utilizing each of the respective luminanceindicators to command uniform luminance among the plurality of graphicsegments, comprising: maintaining the equal magnitude of luminanceintensity in each of the graphic segments to be output from the lightsource, and adjusting one of the scan time and the scan speed for atleast one of the graphic segments based on respective ones of theluminance indicators; and projecting the projected parametric curve uponthe transparent windscreen based on the modified desired parametriccurve.
 15. The method of claim 14, wherein the energy imparted acrosseach of the graphic segments in the desired parametric curve to beprojected is equal.
 16. The method of claim 15, wherein the energyimparted comprises photonic energy.
 17. The method of claim 14, whereinadjusting one of the scan time and the scan speed for at least one ofthe graphic segments based on respective ones of the luminanceindicators comprises: decreasing the scan speed for graphic segmentshaving longer effective scan lengths; and increasing the scan speed forgraphic segments having shorter effective scan lengths.
 18. The methodof claim 14, wherein the distance between each of the plurality ofnon-equidistantly spaced control point decreases as the radius ofcurvature on the desired parametric curve decreases.
 19. The method ofclaim 14, wherein the desired parametric curve is a non-uniform-rationalb-spline parametric curve.
 20. An apparatus to display a projectedparametric curve upon a transparent windscreen head-up display, theapparatus comprising: a graphics system for monitoring a desiredparametric curve to be projected upon the transparent windscreen, thedesired parametric curve comprising a plurality of non-equidistantlyspaced control points and a plurality of graphic segments, wherein eachgraphic segment is between adjacent pairs of the control points andcomprises an equal magnitude of luminance intensity to be projected froma light source; monitoring a respective effective scan length for eachof the plurality of graphic segments, the respective scan length equalto a distance between a respective adjacent pair of control points;determining a respective luminance indicator for each of the pluralityof graphical segments, the luminance indicator indicative of a magnitudeof luminance directly proportional to the effective scan lengthrespective to each graphical segment; when a variance is determinedbetween the respective luminance indicators for at least two of thegraphic segments comprising the equal magnitude of luminance intensityto be projected from the light source, adjusting the magnitude ofluminance intensity of output from the light source for at least one ofthe graphic segments to be projected based on respective ones of theluminance indicators; modifying the desired parametric curve based onthe adjusted magnitude of luminance intensity; and a graphics projectionsystem projecting the projected parametric curve upon the transparentwindscreen head-up display based on the modified desired parametriccurve.